Factors Affecting Frozen Embryo Transfer Success Rates

Factors Affecting Frozen Embryo Transfer Success Rates | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Factors Affecting Frozen Embryo Transfer Success Rates Sholen Acharya, Sheila Balakrishnan, Deepak Rath This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6384128/v1 This work is licensed under a CC BY 4.0 License Status: Published Journal Publication published 25 Oct, 2025 Read the published version in Middle East Fertility Society Journal → Version 1 posted 13 You are reading this latest preprint version Abstract Background This study aims to identify factors influencing the outcomes of frozen embryo transfer (FET) cycles. Methods A prospective observational study was conducted on participants who underwent FET of autologous embryos after endometrial preparation with hormone therapy. Patient characteristics, ovarian stimulation details, and embryo specifics were recorded. Endometrial thickness, morphology, and Doppler flow were assessed on the day of progesterone start. Embryo details on the transfer day were also recorded. Serum ß-hCG levels were measured twelve days post-transfer, and those with levels > 25 IU/L underwent a 6-week ultrasound to detect a gestational sac. The clinical pregnancy rate (CPR) was calculated, and statistical differences between pregnant and non-pregnant groups were evaluated using Chi-square or Fisher’s exact tests for categorical variables and the Mann-Whitney U-test for continuous variables. Logistic regression analysis was used to identify independent variables associated with successful pregnancy outcomes. Results For a total of 190 cycles, the CPR was 35.7%. Univariate logistic regression revealed that antral follicle count (AFC), Anti-Müllerian hormone (AMH), blastocyst transfer, embryo quality, and transferring more than one embryo were significantly associated with CPR. On multivariate analysis, embryo quality remained the only independent predictor of successful FET outcomes. Conclusion Embryo quality is the most significant predictor of successful FET outcomes. Other factors like age, ovarian reserve, number and type of embryo transferred also influence success, further research is needed to understand the role of endometrial factors. Tailored treatment approaches are crucial for optimising IVF success. Clinical pregnancy rate embryo endometrium Anti-Müllerian hormone Antral Follicle Count Blastocyst Figures Figure 1 Figure 2 Figure 3 Figure 4 1. Introduction The first successful human frozen embryo transfer (FET) was performed by Trounson and Mohr in 1983 1 . Since then, advancements in assisted reproductive technology (ART) have made FET a cornerstone of fertility treatment. FET offers multiple advantages, including improved cumulative pregnancy rates 2 , reduced risk of ovarian hyperstimulation syndrome, and a lower incidence of complications associated with multiple pregnancies when combined with elective single embryo transfer 2 . Additionally, FET plays a crucial role in fertility preservation, allowing cancer patients to conceive post-treatment and enabling individuals to delay pregnancy for personal or social reasons. The success of FET depends on various factors, including patient characteristics, embryo quality, and procedural techniques. Several studies have explored predictors of successful FET cycles. Ashrafi et al. found that factors such as the long gonadotropin-releasing hormone (GnRH) agonist protocol, ovarian stimulation with both follicle-stimulating hormone (FSH) and luteinizing hormone (LH), an endometrial thickness greater than 8mm, and a positive outcome in a previous fresh cycle were associated with improved pregnancy rates 3 . Similarly, Eftekar et al. identified a significant correlation between FET success and FSH levels exceeding a threshold of 10 IU/ml 4 . Additionally, a 2013 retrospective study suggested that having a top-quality embryo at any stage of culture enhances success rates, even if those high-quality characteristics diminish before transfer 5 . This study aims to identify the key factors influencing FET outcomes at our public hospital, where cost-effective protocols are implemented. Our centre follows an “all-freeze strategy,” and most embryos are frozen on the second or third day of culture due to the limited availability of a full-time embryologist. By analysing outcomes in this resource-limited setting, this study seeks to isolate the most critical factors contributing to FET success, thereby optimising treatment strategies for improved patient outcomes. 2. Material and methods This prospective observational study was conducted at a tertiary public hospital between July 2020 and December 2021 for 18 months. 2.1. Population and sampling All sub-fertile women undergoing ART (Assisted Reproductive Technology) treatment at the centre were eligible to participate in the study. Women of reproductive age group (21–45 years) undergoing autologous frozen embryo transfer after endometrial preparation done using hormone therapy were included, and those undergoing donor cycles or embryo transfer after preparation of endometrium with methods other than hormone replacement or those who did not provide consent were excluded from the study. Those meeting the study criteria were recruited consecutively within the study period. The study was initiated after receiving ethical approval from the institutional review board. 2.2. Procedure 2.2.1. Preliminary Assessment Subjects were screened for eligibility and clinical characteristics were recorded including demography (age, BMI, years of infertility, primary/secondary infertility, ovarian reserve markers), infertility causes (male, female, combined, or unexplained), ovarian stimulation details, gonadotropin types, and triggers used, sperm parameters and embryo formation details. 2.2.2. Ovarian Stimulation, In-Vitro Fertilization, and Embryo Culture Subjects underwent controlled ovarian hyperstimulation with exogenous gonadotropins using flexible GnRH antagonist or long GnRH agonist protocols. The drug utilized for stimulation was either Human Menopausal Gonadotropin (HMG) [Inj. MENOPUR, FERRING Pharmaceuticals, INDIA] or recombinant FSH (r-FSH) [Inj. GONAL-F, MERCK SERONO, SWITZERLAND] or a combination of both. For some patients, recombinant LH (r-LH) [lutropin alfa; Luveris®, Laboratoires Serono S.A] was added to r-FSH instead of HMG. Oocyte maturation was triggered by either human Chorionic Gonadotropin (hCG) or gonadotropin-releasing hormone agonist (GnRH agonist) or both together (dual trigger) when three follicles reached > 17mm in diameter, and transvaginal follicle aspiration was performed after 35 hours. Fertilization was assessed 16 hours post-ICSI. Embryos were cultured in G-TL media (Vitrolife, Sweden) and cryopreserved at cleavage stages using the Istanbul consensus for grading. 2.2.3. Embryo Freezing (Cryopreservation) Embryos were vitrified using Kitazato Cryotop method 6 and stored in liquid nitrogen at -196°C, under constant monitoring. 2.2.4. Endometrial Preparation for Frozen Embryo Transfer Subjects received 12–14 days of oral contraceptives, followed by endometrial preparation using hormone replacement therapy with or without pituitary suppression. Estrogen was administered, and progesterone was initiated after reaching an endometrial thickness of ≥ 7mm. 2.2.5. Endometrial thickness, morphology, and endometrial doppler on the day of starting progesterone After starting estrogen for endometrial preparation, endometrium was evaluated using transvaginal scan (Voluson E8 ultrasound machine (GE Healthcare South Asia GmbH and Co OG). The greyscale function of the ultrasound machine was used for measuring endometrial thickness. It was measured in the midsagittal plane as the maximum distance between the two interfaces of the endo-myometrial junction (callipers placed along the hyperechoic line adjoining the myometrium) (Fig. 1 ). On the day of the start of progesterone, endometrial thickness, morphology, and Doppler were recorded. Endometrial morphology was divided into two types: type A: triple-line with a hypoechoic endometrium, hyperechoic outer walls, and a central echogenic line; type B: no triple-line, characterised by an isoechoic or homogeneous hyperechoic endometrium Power Doppler was used to evaluate endometrial-subendometrial blood flow. Power Doppler characteristics applied in all examinations were as follows: PD map 5, frequency mid, flow resolution mid1, line filter 3, line density 8, smooth rise 4, smooth fall 6, ensemble 10, artifact suppression on, balance 205, normal quality, the pulse repetition frequency of 300 Hz and wall motion filter low2 (120Hz). The Doppler findings (Fig. 2 ) were summarised using Applebaum criteria 7 : zone 1: vessels penetrating the outer hypoechogenic area but not entering the hyperechogenic margin; zone 2: vessels penetrating the hyperechogenic margin but not entering the hypoechogenic inner area; zone 3: vessels entering the hypoechogenic inner area. 2. 2.6. Embryo Warming and Post-Warming Culture Embryos were warmed according to Kitazato protocol 6 and cultured in G-TL media inside an incubator (MINC mini-incubator, Cook Medical) before transfer. Post-warming culture was done upto day-3 or day-5 based on morphology of embryos on the day of warming. 2.2.7. Embryo Assessment on the Day of Transfer Cleavage-stage embryos and morula were graded according to Istanbul consensus 8 . Good quality cleavage stage embryos on day-3 were those with 6–10 blastomeres, no multinucleated blastomere, and < 25% fragmentation. Good quality morula on day-4 were those where compaction involved the majority of the volume of the embryo. Blastocyst grading was done according to Gardner and Schoolcraft’s (1999) classification system 9 . Good quality blastocysts on day 5 were those where the blastocoel cavity filled the embryo completely with loosely grouped ICM and loose epithelium (≥ 3BB). Good-quality embryos were selected for transfer. 2.2.8. Embryo Transfer Procedure Embryo transfer was performed using soft COOK’s Sydney IVF Catheter under transabdominal ultrasound guidance. Cervical mucus was cleared, and embryos were transferred at a predefined distance from the fundus. The patient rested post-procedure, and progesterone supplementation continued. 2.2.9. Luteal phase support and follow up After the embryo transfer, luteal support was given with vaginal micronized progesterone gel (SUSTEN 8% gel, Sun pharmaceuticals, INDIA). Serum ß-hCG was done 12 days after the embryo transfer and considered positive if > 25 IU/L. Those with positive serum ß-hCG were followed up with a transvaginal scan 6 weeks after embryo transfer for confirmation of clinical pregnancy (defined as the presence of intrauterine sac). Subjects were followed till first-trimester aneuploidy screening between 11–13 weeks to confirm ongoing pregnancy. 2.3. Statistical analysis Data were entered into MS EXCEL file. The clinical pregnancy rate (CPR) was calculated as per the formula $$\:CPR=\frac{Number\:of\:clinical\:pregnancies}{Number\:of\:FET\:cycles}\times\:100$$ Further analysis was performed on SPSS software, version 20.0. Continuous variables were expressed as mean with standard deviation (SD) (normal distribution) or as median with interquartile range (IQR) (non-normal data). Categorical data was represented as proportions with a 95% confidence interval and compared using chi-square test. Quantitative variables were compared using t-test (for normally distribution) or Mann-Whitney U test (non-parametric test). Differences were considered significant if two-tailed p values were < 0.05. Receiver Operating Curve (ROC) analysis was done to evaluate the predictive value of variates for clinical pregnancies. Univariate and multivariate logistic regression analyses were performed to determine the variables independently associated with successful pregnancy outcomes. 3. Results A total of 295 planned frozen embryo transfer (FET) cycles were evaluated for inclusion (Fig. 3 ). However, 27 cycles were cancelled due to patients testing positive for COVID-19, and 4 additional cycles were excluded because the endometrial preparation was carried out using methods other than hormone therapy—one cycle used ovarian stimulation, and three cycles were done with a natural cycle. Among the remaining 264 cycles, 59 were excluded due to thin endometrium, and 15 were cancelled due to pre-transfer COVID-19 positivity Ultimately, 190 cycles were included in the final analysis, involving 170 participants. Among these, 18 participants underwent two FET cycles, and one underwent three FET cycles within the study period. Of the 190 cycles, 181 were performed in “all freeze” cycles, while 9 cycles were conducted following a fresh embryo transfer with surplus embryos. For a comprehensive overview of demographic and clinical parameters of the participants please refer to Acharya et al 10 . 3.1. Clinical Pregnancy Rate across various demographic and clinical parameters The overall clinical pregnancy rate (CPR) was 35.7% per transfer cycle (68 clinical pregnancies out of 190 cycles). The CPR varied across demographic and clinical parameters, as detailed in Table 1 . While age, duration of infertility, BMI, cause of infertility, stimulation protocol, addition of LH, trigger, endometrial preparation protocol, endometrial morphology, endometrial doppler, day of embryo transfer, transfer characters did not show statistically significant differences in CPR, the following factors demonstrated notable associations: anti-müllerian hormone (AMH) with a cutoff value of 1.2 ng/mL was significantly associated with clinical pregnancy (p = 0.021), with higher AMH levels corresponding to increased pregnancy rates; blastocyst transfer had a significantly higher CPR (p = 0.028) than cleavage-stage transfers; high quality embryo and blastocysts were associated with significantly improved pregnancy rates (p < 0.001 and p = 0.002, respectively); number of embryos transferred with single embryo transfers resulted in significantly lower pregnancy rates compared to double embryo transfers (p = 0.004) and triple embryo transfers (p = 0.01). Table 1 Clinical pregnancy rate (CPR) for various groups of parameters Parameter Groups CPR p-value Age < 35 years 39.04 0.089 ≥ 35 years 25 Duration of infertility < 5 years 37.2 0.799 ≥ 5 years 35.2 BMI < 25kg/m2 39.3 0.171 ≥ 25kg/m2 29.4 Type of infertility Primary infertility 37.4 0.489 Secondary infertility 32.2 Cause Female 35.5 0.974 Male 36.6 Combined 33.3 Female factor Endometriosis 30.4 0.201 Hypogonadotropic Hypogonadism 100 PCOS 54.5 Tubal 30 Unexplained 30.2 Uterine 50 Male factor Azoospermia 29.4 0.5011 Severe OAT 39.5 AFC ≤ 5 22.2 0.494 > 5 36.46 AMH ≤ 1.2ng/ml 11.1 0.021 > 1.2 ng/ml 38.37 Stimulation protocol Agonist Protocol 0.76 Antagonist Protocol Addition of LH from start of stimulation Yes 26.8 0.177 No 38.2 Trigger GnRHa 39.7 0.691 hCG 34.2 Number of M2 oocytes 6–12 months 30.30 > 12–24 months 24.39 > 24 months 75 Endometrial preparation HRT without GnRHa 36.6 1 HRT with GnRHa 35.75 Endometrial thickness 8mm 39.5 Endometrial morphology Triple layer 37.2 0.311 Non-triple layer 26.9 Endometrial doppler Zone 1 25 0.368 Zone 2 28.2 Zone 3 38 Day of embryo transfer Day 3 36.61 0.799 Day 5 34.7 Blastocyst transfer yes 44.18 0.028 no 28.84 Embryo quality Good 46.01 < 0.001 Poor 20.77 Blastocyst quality Good Blastocyst 59.5% 0.002 Poor Blastocyst 27.9% Number of transferred embryos Single 13.1 0.004 *p1 = 0.009 *p2 = 0.5 *p3 = 0.01 Double 43.11 Triple 37.2 BMI: Body Mass Index; AFC: Antral Follicle Count; AMH: Anti-Müllerian Hormone; LH: Luteinising Hormone; M2 oocytes: Metaphase II oocytes (mature eggs); SSR: Surgical Sperm Retrieval; PCOS: Polycystic Ovary Syndrome; OAT: Oligoasthenoteratozoospermia; GnRHa: Gonadotropin-Releasing Hormone agonist; hCG: human Chorionic Gonadotropin; *p1- Single vs Double; *p2- Double vs Triple; *p3- Single vs Triple Among quantitative variables (Table 2 ), only antral follicle count (AFC) was significantly different between pregnant and non-pregnant groups (p = 0.047), with higher AFC correlating with increased pregnancy likelihood. No significant differences were observed in age, BMI, duration of infertility, AMH, stimulation characteristics, oocyte yield, time between freezing and transfer, endometrial thickness on the transfer day. Table 2 Summary of quantitative parameters of the study population in the pregnant and non-pregnant groups Clinical pregnancy: Yes n = 68 Clinical pregnancy: No n = 122 Mean ± SD Median (IQR) Mean ± SD Median (IQR) p value Age (years) 31 + 4 32 (28–34) 32 ± 5 32 (29–36) 0.217 $ Duration of infertility (years) 7 ± 4 7 (4–10) 8 ± 4 7 (4–11) 0.34 $ BMI (kg/m 2 ) 24.30 ± 3.25 24.00 (22.00–26.00 24.74 ± 3.88 25.00 (22.00–27.00) 0.310 $ AFC 23 ± 12 20 (14–30) 19 ± 11 16 (10–24) 0.047 $ AMH (ng/ml) 4.12 ± 2.63 3.55 (2.3–5.55) 3.65 ± 2.55 3.1 (1.8–5) 0.115 $ Days of stimulation 9 ± 1 9 (8–9) 9 ± 1 9 (8–10) 0.642 $ E 2 levels on trigger day (pg/ml) 3032 ± 1598 2569 (1893–3944) 3128 ± 1950 2589 (1848–3881) 0.977 $ P 4 levels on trigger day (ng/ml) 0.962 ± 0.590 0.800 (0.500–1.300) 0.984 ± 0.736 0.800 (0.500–1.400) 0.790 $ Total no of oocytes 15 ± 6 15 11–20) 14 ± 7 14(8–20) 0.245 $ M2 oocytes 12 ± 5 11 (8–15) 11 ± 6 11 (6–16) 0.158 $ 2PN No 9 ± 4 8 (6–12) 8 ± 5 7 (4–11) 0.135 $ Total no of embryos formed 9 ± 4 8 (5–11) 8 ± 5 7 (4–10) 0.178 $ No of embryos frozen 5 ± 2 6 (3–7) 5 ± 2 5 (3–6) 0.096 $ Time from IVF (months) 8 ± 6 6 (4–12) 10 ± 6 8 (5–13) 0.056 $ Endometrial thickness (mm) 7.98 ± 1.15 7.9 (7-8.5) 7.86 ± 1.06 7.5 (7–8.5) 0.381 $ BMI: Body Mass Index; AFC: Antral Follicle Count; AMH: Anti-Müllerian Hormone; E 2 : Estrogen; P 4 : Progesterone; M2 oocytes: Metaphase II oocytes (mature eggs); 2PN: fertilized egg with two pronuclei; SD: Standard deviation; IQR: Interquartile range; $ Calculated by Mann Whitney U test 3.2. Predictive Analysis of Clinical Pregnancy Receiver Operating Characteristic (ROC) curve analysis was conducted to evaluate the predictive value of AFC for clinical pregnancy (Table 3 , Fig. 3 ). The area under the ROC curve (AUC) was 0.587 (95% CI: 0.513–0.658, p = 0.0399), indicating poor predictive power. The optimal cutoff for AFC was 11, with 88.24% sensitivity but low specificity (28.69%), suggesting that AFC alone is not a strong predictor of clinical pregnancy. Table 3 Summary of the ROC curve for AFC as a predictor of clinical pregnancy Area under the ROC curve (AUC) 0.587 Standard Error a 0.0423 95% Confidence interval b 0.513 to 0.658 z statistic 2.054 Significance level P (Area = 0.5) 0.0399 Youden index J 0.1692 AFC > 11 Sensitivity 88.24 Specificity 28.69 3.3. Binary Logistic Regression Analysis A binary logistic regression model (Table 4 ) was used to assess the independent effects of significant variables on clinical pregnancy. Key findings include: AFC: Higher AFC was associated with increased pregnancy odds (OR = 1.027, p = 0.038). AMH: AMH levels ≤ 1.2 ng/mL were significantly associated with lower pregnancy likelihood (OR = 0.201, p = 0.036). Blastocyst Transfer: Increased pregnancy odds were observed with blastocyst transfers (OR = 1.84, p = 0.046). Embryo and Blastocyst Quality: High-quality embryos (OR = 3.25, p < 0.001) and high-quality blastocysts (OR = 3.79, p = 0.004) significantly improved pregnancy rates. Number of Embryos Transferred: Double vs. Single: Higher success with double transfers (OR = 5.00, p = 0.002). Triple vs. Single: Triple transfers also showed increased pregnancy likelihood (OR = 3.91, p = 0.018). The Hosmer–Lemeshow goodness-of-fit test indicated an adequate model fit (χ² = 10.634, p = 0.223). The Nagelkerke R² suggested that embryo quality, blastocyst quality and transfer of two or three embryos vs single embryo had the highest predictive potential for clinical pregnancy. Table 4 Summary table of binary logistic regression Variable ß SE p-value OR 95% CI for OR R 2 AFC 0.027 0.013 0.038 1.027 1.001–1.054 0.031 AMH ≤ 1.2ng/ml vs > 1.2 ng/ml -1.606 0.766 0.036 0.201 0.045–0.901 0.044 Blastocyst transfer 0.609 0.305 0.046 1.8401 1.01–3.35 0.028 Embryo quality 1.179 0.338 < 0.001 3.25 1.674–6.309 0.092 Blastocyst quality * 1.335 0.463 0.004 3.79 1.53–9.41 0.132 Double vs single embryos 1.610 0.517 0.002 5.003 1.815–13.793 0.111 Triple vs single embryos 1.364 0.574 0.018 3.91 1.126–12.055 0.111 3.4. Multinomial Logistic Regression Analysis To minimise multicollinearity effects, multinomial logistic regression was conducted using the number of embryos transferred, Blastocyst transfer, blastocyst quality, AMH cut-off ≤ 1.2ng/ml, and AFC. Only embryo quality remained statistically significant (p = 0.006), with high-quality embryos increasing pregnancy likelihood nearly fivefold (ß=1.601, SE:0.578; OR = 4.96, 95% CI: 1.60–15.39). The model had a good fit (χ² = 141.014, p = 0.082) with Nagelkerke R 2 of 0.241. 4. Discussion In our study, embryo quality emerged as the most significant factor influencing clinical pregnancy rates (CPR), consistent with numerous studies that highlight the importance of embryo quality in IVF outcomes 11 . While various other factors also contribute to IVF success, age remains a well-established predictor. Although our results showed a trend toward higher CPR in women under 35 years (40%) compared to those aged 35 and older (25%), the difference was not statistically significant. This could be due to the small sample size of women ≥ 35 years, possibly leading to a type II error. Our findings align with the well-documented decline in ovarian reserve and egg quality beyond 35, which is known to adversely affect IVF success 12 . Additionally, the duration of infertility did not show a significant impact on CPR in our study, which is in line with multiple studies suggesting that the length of infertility does not substantially alter pregnancy outcomes, especially when the cause of infertility is not primarily related to ovarian reserve 4 . Body mass index (BMI) has long been implicated in IVF outcomes, with a higher BMI correlating with a reduced likelihood of pregnancy. Our study found that patients with a BMI < 25 kg/m² had a 10% higher CPR than those with BMI ≥ 25 kg/m², although the difference was not statistically significant. A systematic review by Sermondade et al. confirmed a decrease in live birth probability in individuals with a BMI ≥ 30 kg/m² 13 . These findings underscore the need for further investigation into the role of BMI as a modifiable factor in IVF outcomes, particularly given the rising global obesity rates. Ovarian reserve is a critical factor in predicting IVF success. In our study, expected poor responders according to POSEIDON 14 with AFC ≤ 5 had a CPR of 22%, but the sample size was too small to derive significant conclusions. However, AMH threshold of ≤ 1.2 ng/ml showed a significant difference in CPR, with a CPR of 11% for AMH ≤ 1.2 ng/ml and 38% for AMH > 1.2 ng/ml [p-value 0.021, OR 4.98 (95% CI 1.1–22.4)]. This supports the findings of other studies that have demonstrated the utility of AMH as a marker for ovarian reserve, with lower AMH levels being strongly associated with poorer IVF outcomes. A similar study by Esteves et al. found significant differences in cumulative delivery rates between patients with poor versus normal ovarian reserve, further emphasizing the importance of ovarian reserve in predicting pregnancy success 15 . The choice of ovarian stimulation protocol is a key aspect of IVF treatment, affecting both the quantity and quality of oocytes retrieved. In our study, most patients underwent stimulation with a flexible antagonist protocol, with a CPR of 38%, which is consistent with the average IVF pregnancy rates. The pregnancy rate for those undergoing stimulation with the agonist protocol was considerably lower at 15.7%, although the small sample size of this subgroup limits the generalizability of this result. The comparison between antagonist and agonist protocols has generated controversial outcomes in various studies 16 , 17 . The number of mature oocytes retrieved during IVF is a key factor in determining the chances of pregnancy. Our findings showed that patients with fewer than four oocytes had a much lower CPR of 18%, while those with 10–14 oocytes had a CPR of 45%, and those with more than 15 oocytes had a CPR of 37%. These results align with studies that suggest a higher number of oocytes correlates with better outcomes, although the cumulative live birth rate seems to plateau after a certain point, typically around 15 oocytes 18 . In contrast, both lower and excessively high numbers of oocytes are associated with reduced success rates. This finding suggests that targeting an optimal range of oocytes, typically between 5 and 15, may enhance the chances of pregnancy, particularly in the context of FET cycles. Embryo quality is perhaps the most critical determinant of IVF success. Our study found a significant difference in CPR between good and poor-quality embryos, with good-quality embryos showing a CPR of 46%, compared to only 18% for poor-quality embryos [p-value < 0.001) with OR 3.9 (95% CI 1.98–7.6)]. This aligns with the body of evidence indicating that top-quality embryos result in significantly higher pregnancy rates 19 . Moreover, when comparing blastocyst transfers to cleavage-stage embryo transfers, we observed that blastocyst transfer had a CPR of 44%, significantly higher than the 28% CPR for non-blastocyst transfers. These findings support the literature, which consistently shows that blastocyst transfers offer a better chance of pregnancy, as blastocysts are more likely to implant successfully due to their advanced developmental stage 20 . Additionally, the number of embryos transferred is an important factor. Our study showed that double and triple embryo transfers had significantly higher CPRs (43%) compared to single embryo transfer (13%). While a single embryo transfer carries a lower risk of multiple pregnancies, our results highlight the four to five times higher odds of pregnancy with double and triple embryo transfers. This finding is consistent with the general IVF literature, which suggests that transferring multiple embryos increases the likelihood of pregnancy, albeit with the associated risks of multiple pregnancies 21 . The role of endometrial factors in IVF success, including endometrial thickness, morphology, and blood flow, has been widely debated. In our study, endometrial thickness did not significantly correlate with clinical pregnancy rates (CPR), although thicker endometrium showed a trend toward slightly improved chances of pregnancy. Other studies, such as one by Shaodi et al., have demonstrated a significant correlation between endometrial thickness and pregnancy rates, especially when the thickness exceeds 8mm 22 . Moreover, the presence of a triple-layer endometrial pattern was associated with a 10% higher success rate compared to non-triple-layer patterns, although the difference was not statistically significant in our cohort similar to earlier studies 23 . Endometrial blood flow, as assessed by Doppler, showed a 10% higher but non-significant difference in CPR for zone 3 compared to zones 1 and 2, aligning with existing research 24 . Despite trends suggesting endometrial factors impact IVF success, larger studies are needed to confirm their clinical significance in improving outcomes. 5. Conclusion In conclusion, while embryo quality remains the most important predictor of IVF success, several other factors—such as age, ovarian reserve, number and type of embryo transferred—play significant roles. Endometrial factors, though important, require further investigation to fully elucidate their impact on IVF success. These findings underline the complexity of IVF outcomes and the need for personalized treatment approaches that consider a range of variables to optimize success rates. Abbreviations FET- Frozen embryo transfer CPR- Clinical Pregnancy Rate GnRH- Gonadotropin-Releasing Hormone FSH- Follicle Stimulating Hormone LH- Luteinizing Hormone ART- Assisted Reproductive Technology BMI- Basal Metabolic Rate r-FSH- recombinant Follicle Stimulating Hormone r-LH- recombinant Luteinizing Hormone HMG- Human Menopausal Gonadotropins hCG- human Chorionic Gonadotropin ICSI- Intra-Cytoplasmic Sperm Injection ICM- Inner Cell Mass IVF- In-vitro fertilization SD- Standard Deviation IQR- Interquartile Range ROC- Receiver Operating Curve AMH- Anti-Müllerian hormone AFC- Antral Follicle Count M2- Metaphase II SSR- Surgical Sperm Retrieval PCOS- Polycystic Ovary Syndrome OAT- Oligoasthenoteratozoospermia 2PN- Two Pronuclei POSEIDON- Patient-Oriented Strategies Encompassing Individualized Oocyte Declarations Ethics approval and consent to participate The study protocol was approved by the Institutional Review Committee (IRC), and Human Ethics Committee (HEC) of Government Medical College, Thiruvananthapuram vide letter no: HEC.No.04/92/2020/MCT dated 26/06/2020. Written informed consent was obtained from participants. Consent for publication Informed consent for publication was provided by the participants. Availability of data and material The datasets generated and/or analysed during the current study are available in the Mendeley data repository, DOI: 10.17632/hp9n9w6w2f.1 Competing interests The authors declare that there is no conflict of interest. Funding None received Authors' contributions SA- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing. SB- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing. DR- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing. Acknowledgements None References Trounson A, Mohr L. Human pregnancy following cryopreservation, thawing and transfer of an eight-cell embryo. Nature . 1983;305(5936):707-709. doi:10.1038/305707a0 Tiitinen A. Elective single embryo transfer: the value of cryopreservation. Human Reproduction . 2001;16(6):1140-1144. doi:10.1093/humrep/16.6.1140 Ashrafi M, Jahangiri N, Hassani F, Akhoond MR, Madani T. The factors affecting the outcome of frozen–thawed embryo transfer cycle. Taiwanese Journal of Obstetrics and Gynecology . 2011;50(2):159-164. doi:10.1016/j.tjog.2011.01.037 Eftekhar M, Rahmani E, Pourmasumi S. Evaluation of clinical factors influencing pregnancy rate in frozen embryo transfer. Iran J Reprod Med . 2014;12(7):513-518. Veleva Z, Orava M, Nuojua-Huttunen S, Tapanainen JS, Martikainen H. Factors affecting the outcome of frozen-thawed embryo transfer. Human Reproduction . 2013;28(9):2425-2431. doi:10.1093/humrep/det251 Huang TTF. The kitazato “closed” cryotop sc vitrification system performs comparably to its original “open” system. a study using unfertilized human eggs, mouse eggs, and mouse embryos. Fertility and Sterility . 2016;105(2):e22-e23. doi:10.1016/j.fertnstert.2015.12.072 Applebaum M. The uterine biophysical profile. Ultrasound in Obstet & Gyne . 1995;5(1):67-68. doi:10.1046/j.1469-0705.1995.05010067.x Alpha Scientists in Reproductive Medicine and ESHRE Special Interest Group of Embryology, Balaban B, Brison D, et al. The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting. Human Reproduction . 2011;26(6):1270-1283. doi:10.1093/humrep/der037 Gardner DK, Schoolcraft WB. Culture and transfer of human blastocysts: Current Opinion in Obstetrics and Gynaecology . 1999;11(3):307-311. doi:10.1097/00001703-199906000-00013 Acharya S, Balakrishnan S, Rath D. Pregnancy Rates After Frozen Embryo Transfer: Insights from an Indian Government Hospital. IJMRGE . 2025;6(2):965-972. doi:10.54660/.IJMRGE.2025.6.2.965-972 Oron G, Son WY, Buckett W, Tulandi T, Holzer H. The association between embryo quality and perinatal outcome of singletons born after single embryo transfers: a pilot study. Human Reproduction . 2014;29(7):1444-1451. doi:10.1093/humrep/deu079 Sun YF, Zhang J, Xu YM, et al. Effects of age on pregnancy outcomes in patients with simple tubal factor infertility receiving frozen-thawed embryo transfer. Sci Rep . 2020;10(1):18121. doi:10.1038/s41598-020-75124-3 Sermondade N, Huberlant S, Bourhis-Lefebvre V, et al. Female obesity is negatively associated with live birth rate following IVF: a systematic review and meta-analysis. Human Reproduction Update . 2019;25(4):439-451. doi:10.1093/humupd/dmz011 Grisendi V, Mastellari E, La Marca A. Ovarian Reserve Markers to Identify Poor Responders in the Context of Poseidon Classification. Front Endocrinol . 2019;10:281. doi:10.3389/fendo.2019.00281 Esteves SC, Yarali H, Vuong LN, et al. Cumulative delivery rate per aspiration IVF/ICSI cycle in POSEIDON patients: a real-world evidence study of 9073 patients. Human Reproduction . 2021;36(8):2157-2169. doi:10.1093/humrep/deab152 Lai Q, Zhang H, Zhu G, et al. Comparison of the GnRH agonist and antagonist protocol on the same patients in assisted reproduction during controlled ovarian stimulation cycles. Int J Clin Exp Pathol . 2013;6(9):1903-1910. Al-Mousawi BJ, Al-Azzam MAH, Al-Zahawi B, Fawzi HA. Agonist Versus Antagonist in Intracytoplasmic Sperm Injection Cycles: Which Is the Best? International Journal of Women’s Health and Reproduction Sciences . 2019;8(3):285-289. doi:10.15296/ijwhr.2020.46 Timeva T, Milachich T, Antonova I, Arabaji T, Shterev A, Omar HA. Correlation Between Number of Retrieved Oocytes and Pregnancy Rate After In Vitro Fertilization/IntraCytoplasmic Sperm Infection. The Scientific World JOURNAL . 2006;6:686-690. doi:10.1100/tsw.2006.145 De Neubourg D. Single top quality embryo transfer as a model for prediction of early pregnancy outcome. Human Reproduction . 2004;19(6):1476-1479. doi:10.1093/humrep/deh283 Gardner DK, Lane M, Stevens J, Schlenker T, Schoolcraft WB. Blastocyst score affects implantation and pregnancy outcome: towards a single blastocyst transfer. Fertility and Sterility . 2000;73(6):1155-1158. doi:10.1016/S0015-0282(00)00518-5 Thurin A, Hausken J, Hillensjö T, et al. Elective Single-Embryo Transfer versus Double-Embryo Transfer in in Vitro Fertilization. N Engl J Med . 2004;351(23):2392-2402. doi:10.1056/NEJMoa041032 Shaodi Z, Qiuyuan L, Yisha Y, Cuilian Z. The effect of endometrial thickness on pregnancy outcomes of frozen-thawed embryo transfer cycles which underwent hormone replacement therapy. Yu Y, ed. PLoS ONE . 2020;15(9):e0239120. doi:10.1371/journal.pone.0239120 Yang W, Zhang T, Li Z, et al. Combined analysis of endometrial thickness and pattern in predicting clinical outcomes of frozen embryo transfer cycles with morphological good-quality blastocyst: A retrospective cohort study. Medicine . 2018;97(2):e9577. doi:10.1097/MD.0000000000009577 Chien LW, Au HK, Chen PL, Xiao J, Tzeng CR. Assessment of uterine receptivity by the endometrial-subendometrial blood flow distribution pattern in women undergoing in vitro fertilization-embryo transfer. Fertility and Sterility . 2002;78(2):245-251. doi:10.1016/S0015-0282(02)03223-5 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Published Journal Publication published 25 Oct, 2025 Read the published version in Middle East Fertility Society Journal → Version 1 posted Editorial decision: Revision requested 14 Sep, 2025 Reviews received at journal 11 Sep, 2025 Reviews received at journal 10 Sep, 2025 Reviewers agreed at journal 09 Sep, 2025 Reviewers agreed at journal 08 Sep, 2025 Reviews received at journal 02 Sep, 2025 Reviews received at journal 30 Aug, 2025 Reviewers agreed at journal 14 Aug, 2025 Reviewers agreed at journal 14 Aug, 2025 Reviewers invited by journal 02 Aug, 2025 Editor assigned by journal 19 Apr, 2025 Submission checks completed at journal 07 Apr, 2025 First submitted to journal 05 Apr, 2025 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6384128","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":439421638,"identity":"79479b8a-cc72-45b5-8f0f-12dc763eb5dd","order_by":0,"name":"Sholen Acharya","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABAElEQVRIiWNgGAWjYDACCQbGAyDaAMyrAGJm5gZCWhiQtJwBaWEkRQtjG5jEr0V+dvOBAx932Mmbs599JvFzXm00fztQy4+KbTi1GNw5lnBw5plkw5096WaSvduO5844zNjA2HPmNm4tEjkGh3nbmBMMDqSxSfBuO5bbANTCzNiGW4v8DKCWv231CQbnn7FJ/p1zLHc+IS0MN4BaGNsOJxjcSGOT5m2oyd1ASAtQZcLB3rbjhhtuPGO2ljl2IHcjUMtBfH6Rn5F88MHPtmp5g/NpjDff1NTlzjt/+OCDHxV4HIYEWIBxdBjMOkCUeiBg/sDAUEes4lEwCkbBKBhBAADK8GEl1mKpgwAAAABJRU5ErkJggg==","orcid":"","institution":"Government Medical College, Thiruvananthapuram","correspondingAuthor":true,"prefix":"","firstName":"Sholen","middleName":"","lastName":"Acharya","suffix":""},{"id":439421639,"identity":"7e6d8c6b-5be4-416d-8bec-904ed598b2f0","order_by":1,"name":"Sheila Balakrishnan","email":"","orcid":"","institution":"Government Medical College, Thiruvananthapuram","correspondingAuthor":false,"prefix":"","firstName":"Sheila","middleName":"","lastName":"Balakrishnan","suffix":""},{"id":439421643,"identity":"fb7d84bc-9d5d-4d9d-b00f-9efcdf9ccb5b","order_by":2,"name":"Deepak Rath","email":"","orcid":"","institution":"John H. Stroger, Jr. Hospital of Cook County","correspondingAuthor":false,"prefix":"","firstName":"Deepak","middleName":"","lastName":"Rath","suffix":""}],"badges":[],"createdAt":"2025-04-05 23:53:06","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6384128/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6384128/v1","draftVersion":[],"editorialEvents":[{"content":"https://doi.org/10.1186/s43043-025-00263-4","type":"published","date":"2025-10-25T16:17:05+00:00"}],"editorialNote":"","failedWorkflow":false,"files":[{"id":80209389,"identity":"3f4339da-04dd-4212-a0a6-bab32bd3f118","added_by":"auto","created_at":"2025-04-09 08:29:38","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":254248,"visible":true,"origin":"","legend":"\u003cp\u003eEndometrial Thickness measurement by grey-scale ultrasonography; Source: Author\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-6384128/v1/d73d4ea2976ab2a9ab95be16.png"},{"id":80209984,"identity":"94e2bc28-f681-409c-a9e3-48b79a5a4d9e","added_by":"auto","created_at":"2025-04-09 08:37:38","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":247317,"visible":true,"origin":"","legend":"\u003cp\u003eEndometrial doppler zones on ultrasonography; Source Author\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-6384128/v1/734aca78d1529c2b7512d325.png"},{"id":80210928,"identity":"ae268385-bd5a-4bb8-b3aa-f88af34fd3fa","added_by":"auto","created_at":"2025-04-09 08:45:38","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":144622,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of included study participants\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-6384128/v1/7d6eff97ca1b0a3489230d38.png"},{"id":80209394,"identity":"2b15e647-fcea-4d36-9f6c-4ae59612d4f0","added_by":"auto","created_at":"2025-04-09 08:29:38","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":420225,"visible":true,"origin":"","legend":"\u003cp\u003eROC curve for AFC as a predictor of clinical pregnancy\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-6384128/v1/4ecd7f13e8f3945154c584d5.png"},{"id":94490260,"identity":"0d0d4121-ea43-472d-be19-4e452af2f301","added_by":"auto","created_at":"2025-10-27 17:08:43","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2086569,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6384128/v1/4922c0a5-9d46-448a-845e-cec93be30028.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Factors Affecting Frozen Embryo Transfer Success Rates","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eThe first successful human frozen embryo transfer (FET) was performed by Trounson and Mohr in 1983 \u003csup\u003e1\u003c/sup\u003e. Since then, advancements in assisted reproductive technology (ART) have made FET a cornerstone of fertility treatment. FET offers multiple advantages, including improved cumulative pregnancy rates \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e, reduced risk of ovarian hyperstimulation syndrome, and a lower incidence of complications associated with multiple pregnancies when combined with elective single embryo transfer \u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e. Additionally, FET plays a crucial role in fertility preservation, allowing cancer patients to conceive post-treatment and enabling individuals to delay pregnancy for personal or social reasons.\u003c/p\u003e \u003cp\u003eThe success of FET depends on various factors, including patient characteristics, embryo quality, and procedural techniques. Several studies have explored predictors of successful FET cycles. Ashrafi et al. found that factors such as the long gonadotropin-releasing hormone (GnRH) agonist protocol, ovarian stimulation with both follicle-stimulating hormone (FSH) and luteinizing hormone (LH), an endometrial thickness greater than 8mm, and a positive outcome in a previous fresh cycle were associated with improved pregnancy rates \u003csup\u003e\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e\u003c/sup\u003e. Similarly, Eftekar et al. identified a significant correlation between FET success and FSH levels exceeding a threshold of 10 IU/ml \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Additionally, a 2013 retrospective study suggested that having a top-quality embryo at any stage of culture enhances success rates, even if those high-quality characteristics diminish before transfer \u003csup\u003e\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThis study aims to identify the key factors influencing FET outcomes at our public hospital, where cost-effective protocols are implemented. Our centre follows an \u0026ldquo;all-freeze strategy,\u0026rdquo; and most embryos are frozen on the second or third day of culture due to the limited availability of a full-time embryologist. By analysing outcomes in this resource-limited setting, this study seeks to isolate the most critical factors contributing to FET success, thereby optimising treatment strategies for improved patient outcomes.\u003c/p\u003e"},{"header":"2. Material and methods","content":"\u003cp\u003e\u003cspan\u003eThis prospective observational study was conducted at a tertiary public hospital between July 2020 and December 2021 for 18 months.\u003c/span\u003e\u003c/p\u003e \u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Population and sampling\u003c/h2\u003e \u003cp\u003eAll sub-fertile women undergoing ART (Assisted Reproductive Technology) treatment at the centre were eligible to participate in the study. Women of reproductive age group (21\u0026ndash;45 years) undergoing autologous frozen embryo transfer after endometrial preparation done using hormone therapy were included, and those undergoing donor cycles or embryo transfer after preparation of endometrium with methods other than hormone replacement or those who did not provide consent were excluded from the study. Those meeting the study criteria were recruited consecutively within the study period. The study was initiated after receiving ethical approval from the institutional review board.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. Procedure\u003c/h2\u003e \u003cdiv id=\"Sec5\" class=\"Section3\"\u003e \u003ch2\u003e2.2.1. Preliminary Assessment\u003c/h2\u003e \u003cp\u003eSubjects were screened for eligibility and clinical characteristics were recorded including demography (age, BMI, years of infertility, primary/secondary infertility, ovarian reserve markers), infertility causes (male, female, combined, or unexplained), ovarian stimulation details, gonadotropin types, and triggers used, sperm parameters and embryo formation details.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section3\"\u003e \u003ch2\u003e2.2.2. Ovarian Stimulation, In-Vitro Fertilization, and Embryo Culture\u003c/h2\u003e \u003cp\u003eSubjects underwent controlled ovarian hyperstimulation with exogenous gonadotropins using flexible GnRH antagonist or long GnRH agonist protocols. The drug utilized for stimulation was either Human Menopausal Gonadotropin (HMG) [Inj. MENOPUR, FERRING Pharmaceuticals, INDIA] or recombinant FSH (r-FSH) [Inj. GONAL-F, MERCK SERONO, SWITZERLAND] or a combination of both. For some patients, recombinant LH (r-LH) [lutropin alfa; Luveris\u0026reg;, Laboratoires Serono S.A] was added to r-FSH instead of HMG. Oocyte maturation was triggered by either human Chorionic Gonadotropin (hCG) or gonadotropin-releasing hormone agonist (GnRH agonist) or both together (dual trigger) when three follicles reached\u0026thinsp;\u0026gt;\u0026thinsp;17mm in diameter, and transvaginal follicle aspiration was performed after 35 hours. Fertilization was assessed 16 hours post-ICSI. Embryos were cultured in G-TL media (Vitrolife, Sweden) and cryopreserved at cleavage stages using the Istanbul consensus for grading.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section3\"\u003e \u003ch2\u003e2.2.3. Embryo Freezing (Cryopreservation)\u003c/h2\u003e \u003cp\u003eEmbryos were vitrified using Kitazato Cryotop method \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e and stored in liquid nitrogen at -196\u0026deg;C, under constant monitoring.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec8\" class=\"Section3\"\u003e \u003ch2\u003e2.2.4. Endometrial Preparation for Frozen Embryo Transfer\u003c/h2\u003e \u003cp\u003eSubjects received 12\u0026ndash;14 days of oral contraceptives, followed by endometrial preparation using hormone replacement therapy with or without pituitary suppression. Estrogen was administered, and progesterone was initiated after reaching an endometrial thickness of \u0026ge;\u0026thinsp;7mm.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e \u003ch2\u003e2.2.5. Endometrial thickness, morphology, and endometrial doppler on the day of starting progesterone\u003c/h2\u003e \u003cp\u003eAfter starting estrogen for endometrial preparation, endometrium was evaluated using transvaginal scan (Voluson E8 ultrasound machine (GE Healthcare South Asia GmbH and Co OG). The greyscale function of the ultrasound machine was used for measuring endometrial thickness. It was measured in the midsagittal plane as the maximum distance between the two interfaces of the endo-myometrial junction (callipers placed along the hyperechoic line adjoining the myometrium) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). On the day of the start of progesterone, endometrial thickness, morphology, and Doppler were recorded. Endometrial morphology was divided into two types: type A: triple-line with a hypoechoic endometrium, hyperechoic outer walls, and a central echogenic line; type B: no triple-line, characterised by an isoechoic or homogeneous hyperechoic endometrium\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003ePower Doppler was used to evaluate endometrial-subendometrial blood flow. Power Doppler characteristics applied in all examinations were as follows: PD map 5, frequency mid, flow resolution mid1, line filter 3, line density 8, smooth rise 4, smooth fall 6, ensemble 10, artifact suppression on, balance 205, normal quality, the pulse repetition frequency of 300 Hz and wall motion filter low2 (120Hz). The Doppler findings (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e) were summarised using Applebaum criteria \u003csup\u003e\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e\u003c/sup\u003e: zone 1: vessels penetrating the outer hypoechogenic area but not entering the hyperechogenic margin; zone 2: vessels penetrating the hyperechogenic margin but not entering the hypoechogenic inner area; zone 3: vessels entering the hypoechogenic inner area.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec10\" class=\"Section3\"\u003e \u003ch2\u003e2.\u003cb\u003e2.6. Embryo Warming and Post-Warming Culture\u003c/b\u003e\u003c/h2\u003e \u003cp\u003eEmbryos were warmed according to Kitazato protocol \u003csup\u003e\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u003c/sup\u003e and cultured in G-TL media inside an incubator (MINC mini-incubator, Cook Medical) before transfer. Post-warming culture was done upto day-3 or day-5 based on morphology of embryos on the day of warming.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section3\"\u003e \u003ch2\u003e2.2.7. Embryo Assessment on the Day of Transfer\u003c/h2\u003e \u003cp\u003eCleavage-stage embryos and morula were graded according to Istanbul consensus \u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Good quality cleavage stage embryos on day-3 were those with 6\u0026ndash;10 blastomeres, no multinucleated blastomere, and \u0026lt;\u0026thinsp;25% fragmentation. Good quality morula on day-4 were those where compaction involved the majority of the volume of the embryo. Blastocyst grading was done according to Gardner and Schoolcraft\u0026rsquo;s (1999) classification system \u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e. Good quality blastocysts on day 5 were those where the blastocoel cavity filled the embryo completely with loosely grouped ICM and loose epithelium (\u0026ge;\u0026thinsp;3BB). Good-quality embryos were selected for transfer.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e \u003ch2\u003e2.2.8. Embryo Transfer Procedure\u003c/h2\u003e \u003cp\u003eEmbryo transfer was performed using soft COOK\u0026rsquo;s Sydney IVF Catheter under transabdominal ultrasound guidance. Cervical mucus was cleared, and embryos were transferred at a predefined distance from the fundus. The patient rested post-procedure, and progesterone supplementation continued.\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec13\" class=\"Section3\"\u003e \u003ch2\u003e2.2.9. Luteal phase support and follow up\u003c/h2\u003e \u003cp\u003eAfter the embryo transfer, luteal support was given with vaginal micronized progesterone gel (SUSTEN 8% gel, Sun pharmaceuticals, INDIA). Serum \u0026szlig;-hCG was done 12 days after the embryo transfer and considered positive if\u0026thinsp;\u0026gt;\u0026thinsp;25 IU/L. Those with positive serum \u0026szlig;-hCG were followed up with a transvaginal scan 6 weeks after embryo transfer for confirmation of clinical pregnancy (defined as the presence of intrauterine sac). Subjects were followed till first-trimester aneuploidy screening between 11\u0026ndash;13 weeks to confirm ongoing pregnancy.\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv id=\"Sec14\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Statistical analysis\u003c/h2\u003e \u003cp\u003eData were entered into MS EXCEL file. The clinical pregnancy rate (CPR) was calculated as per the formula\u003cdiv id=\"Equa\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equa\" name=\"EquationSource\"\u003e\n$$\\:CPR=\\frac{Number\\:of\\:clinical\\:pregnancies}{Number\\:of\\:FET\\:cycles}\\times\\:100$$\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e \u003cp\u003eFurther analysis was performed on SPSS software, version 20.0. Continuous variables were expressed as mean with standard deviation (SD) (normal distribution) or as median with interquartile range (IQR) (non-normal data). Categorical data was represented as proportions with a 95% confidence interval and compared using chi-square test. Quantitative variables were compared using t-test (for normally distribution) or Mann-Whitney U test (non-parametric test). Differences were considered significant if two-tailed p values were \u0026lt;\u0026thinsp;0.05. Receiver Operating Curve (ROC) analysis was done to evaluate the predictive value of variates for clinical pregnancies. Univariate and multivariate logistic regression analyses were performed to determine the variables independently associated with successful pregnancy outcomes.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eA total of 295 planned frozen embryo transfer (FET) cycles were evaluated for inclusion (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). However, 27 cycles were cancelled due to patients testing positive for COVID-19, and 4 additional cycles were excluded because the endometrial preparation was carried out using methods other than hormone therapy\u0026mdash;one cycle used ovarian stimulation, and three cycles were done with a natural cycle. Among the remaining 264 cycles, 59 were excluded due to thin endometrium, and 15 were cancelled due to pre-transfer COVID-19 positivity\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eUltimately, 190 cycles were included in the final analysis, involving 170 participants. Among these, 18 participants underwent two FET cycles, and one underwent three FET cycles within the study period. Of the 190 cycles, 181 were performed in \u0026ldquo;all freeze\u0026rdquo; cycles, while 9 cycles were conducted following a fresh embryo transfer with surplus embryos. For a comprehensive overview of demographic and clinical parameters of the participants please refer to Acharya et al \u003csup\u003e\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cdiv id=\"Sec16\" class=\"Section2\"\u003e \u003ch2\u003e3.1. Clinical Pregnancy Rate across various demographic and clinical parameters\u003c/h2\u003e \u003cp\u003eThe overall clinical pregnancy rate (CPR) was 35.7% per transfer cycle (68 clinical pregnancies out of 190 cycles). The CPR varied across demographic and clinical parameters, as detailed in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e. While age, duration of infertility, BMI, cause of infertility, stimulation protocol, addition of LH, trigger, endometrial preparation protocol, endometrial morphology, endometrial doppler, day of embryo transfer, transfer characters did not show statistically significant differences in CPR, the following factors demonstrated notable associations: anti-m\u0026uuml;llerian hormone (AMH) with a cutoff value of 1.2 ng/mL was significantly associated with clinical pregnancy (p\u0026thinsp;=\u0026thinsp;0.021), with higher AMH levels corresponding to increased pregnancy rates; blastocyst transfer had a significantly higher CPR (p\u0026thinsp;=\u0026thinsp;0.028) than cleavage-stage transfers; high quality embryo and blastocysts were associated with significantly improved pregnancy rates (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 and p\u0026thinsp;=\u0026thinsp;0.002, respectively); number of embryos transferred with single embryo transfers resulted in significantly lower pregnancy rates compared to double embryo transfers (p\u0026thinsp;=\u0026thinsp;0.004) and triple embryo transfers (p\u0026thinsp;=\u0026thinsp;0.01).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eClinical pregnancy rate (CPR) for various groups of parameters\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eParameter\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGroups\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eCPR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;35 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.04\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.089\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;35 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDuration of infertility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;5 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.799\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;5 years\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBMI\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;25kg/m2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.171\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;25kg/m2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eType of infertility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePrimary infertility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.489\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSecondary infertility\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eCause\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eFemale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e0.974\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.6\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCombined\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e33.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003eFemale factor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eEndometriosis\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"5\" rowspan=\"6\"\u003e \u003cp\u003e0.201\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHypogonadotropic Hypogonadism\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e100\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePCOS\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e54.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTubal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUnexplained\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eUterine\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eMale factor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAzoospermia\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e29.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.5011\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSevere OAT\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAFC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e22.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.494\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.46\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAMH\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026le;\u0026thinsp;1.2ng/ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e0.021\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;1.2 ng/ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.37\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eStimulation protocol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAgonist Protocol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.76\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eAntagonist Protocol\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eAddition of LH from start of stimulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.177\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eTrigger\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGnRHa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.691\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ehCG\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003eNumber of M2 oocytes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e18.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"3\" rowspan=\"4\"\u003e \u003cp\u003e0.124\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4\u0026ndash;9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.3\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10\u0026ndash;14\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026ge;\u0026thinsp;15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eSSR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eYes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e16.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.218\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNo\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003eTime from freezing to thawing (transfer)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0\u0026ndash;3 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e42.42\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"4\" rowspan=\"5\"\u003e \u003cp\u003e0.073\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3\u0026ndash;6 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45.65\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;6\u0026ndash;12 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e30.30\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;12\u0026ndash;24 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.39\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;24 months\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEndometrial preparation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHRT without GnRHa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e1\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eHRT with GnRHa\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e35.75\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eEndometrial thickness\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;7 mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e50\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e0.499\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7-8mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;8mm\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e39.5\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEndometrial morphology\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTriple layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.311\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eNon-triple layer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e26.9\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eEndometrial doppler\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZone 1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e0.368\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZone 2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eZone 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e38\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eDay of embryo transfer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDay 3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e36.61\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e0.799\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDay 5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e34.7\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBlastocyst transfer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eyes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e44.18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e0.028\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eno\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e28.84\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eEmbryo quality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGood\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46.01\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e\u0026lt;\u0026thinsp;0.001\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePoor\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20.77\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003eBlastocyst quality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eGood Blastocyst\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e59.5%\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"1\" rowspan=\"2\"\u003e \u003cp\u003e\u003cb\u003e0.002\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003ePoor Blastocyst\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e27.9%\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003eNumber of transferred embryos\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eSingle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e13.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\" morerows=\"2\" rowspan=\"3\"\u003e \u003cp\u003e\u003cb\u003e0.004\u003c/b\u003e\u003c/p\u003e \u003cp\u003e\u003cb\u003e*p1\u0026thinsp;=\u0026thinsp;0.009\u003c/b\u003e\u003c/p\u003e \u003cp\u003e*p2\u0026thinsp;=\u0026thinsp;0.5\u003c/p\u003e \u003cp\u003e\u003cb\u003e*p3\u0026thinsp;=\u0026thinsp;0.01\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDouble\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e43.11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eTriple\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e37.2\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eBMI: Body Mass Index; AFC: Antral Follicle Count; AMH: Anti-M\u0026uuml;llerian Hormone; LH: Luteinising Hormone; M2 oocytes: Metaphase II oocytes (mature eggs); SSR: Surgical Sperm Retrieval; PCOS: Polycystic Ovary Syndrome; OAT: Oligoasthenoteratozoospermia; GnRHa: Gonadotropin-Releasing Hormone agonist; hCG: human Chorionic Gonadotropin; *p1- Single vs Double; *p2- Double vs Triple; *p3- Single vs Triple\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eAmong quantitative variables (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e), only antral follicle count (AFC) was significantly different between pregnant and non-pregnant groups (p\u0026thinsp;=\u0026thinsp;0.047), with higher AFC correlating with increased pregnancy likelihood. No significant differences were observed in age, BMI, duration of infertility, AMH, stimulation characteristics, oocyte yield, time between freezing and transfer, endometrial thickness on the transfer day.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of quantitative parameters of the study population in the pregnant and non-pregnant groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"6\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003eClinical pregnancy: Yes\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;68\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colspan=\"2\" nameend=\"c5\" namest=\"c4\"\u003e \u003cp\u003eClinical pregnancy: No\u003c/p\u003e \u003cp\u003en\u0026thinsp;=\u0026thinsp;122\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e\u0026nbsp;\u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003eMedian (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003eMean\u0026thinsp;\u0026plusmn;\u0026thinsp;SD\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003eMedian (IQR)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003ep value\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e31\u0026thinsp;+\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e32 (28\u0026ndash;34)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e32\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e32 (29\u0026ndash;36)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.217\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDuration of infertility (years)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7 (4\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (4\u0026ndash;11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.34\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e24.30\u0026thinsp;\u0026plusmn;\u0026thinsp;3.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.00 (22.00\u0026ndash;26.00\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e24.74\u0026thinsp;\u0026plusmn;\u0026thinsp;3.88\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e25.00 (22.00\u0026ndash;27.00)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.310\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAFC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23\u0026thinsp;\u0026plusmn;\u0026thinsp;12\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e20 (14\u0026ndash;30)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e19\u0026thinsp;\u0026plusmn;\u0026thinsp;11\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e16 (10\u0026ndash;24)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e\u003cb\u003e0.047\u003c/b\u003e\u003csup\u003e\u003cb\u003e$\u003c/b\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAMH (ng/ml)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.12\u0026thinsp;\u0026plusmn;\u0026thinsp;2.63\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e3.55 (2.3\u0026ndash;5.55)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3.65\u0026thinsp;\u0026plusmn;\u0026thinsp;2.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.1 (1.8\u0026ndash;5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.115\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDays of stimulation\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e9 (8\u0026ndash;9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e9\u0026thinsp;\u0026plusmn;\u0026thinsp;1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e9 (8\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.642\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eE\u003csub\u003e2\u003c/sub\u003e levels on trigger day (pg/ml)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3032\u0026thinsp;\u0026plusmn;\u0026thinsp;1598\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2569 (1893\u0026ndash;3944)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e3128\u0026thinsp;\u0026plusmn;\u0026thinsp;1950\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e2589 (1848\u0026ndash;3881)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.977\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eP\u003csub\u003e4\u003c/sub\u003e levels on trigger day (ng/ml)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.962\u0026thinsp;\u0026plusmn;\u0026thinsp;0.590\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.800 (0.500\u0026ndash;1.300)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.984\u0026thinsp;\u0026plusmn;\u0026thinsp;0.736\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.800 (0.500\u0026ndash;1.400)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.790\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal no of oocytes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e15\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15 11\u0026ndash;20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e14\u0026thinsp;\u0026plusmn;\u0026thinsp;7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e14(8\u0026ndash;20)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.245\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eM2 oocytes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e12\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e11 (8\u0026ndash;15)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e11\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e11 (6\u0026ndash;16)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.158\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e2PN No\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (6\u0026ndash;12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (4\u0026ndash;11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.135\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTotal no of embryos formed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e9\u0026thinsp;\u0026plusmn;\u0026thinsp;4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e8 (5\u0026ndash;11)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7 (4\u0026ndash;10)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.178\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNo of embryos frozen\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (3\u0026ndash;7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e5\u0026thinsp;\u0026plusmn;\u0026thinsp;2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5 (3\u0026ndash;6)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.096\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTime from IVF (months)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e8\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e6 (4\u0026ndash;12)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e10\u0026thinsp;\u0026plusmn;\u0026thinsp;6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e8 (5\u0026ndash;13)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.056\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEndometrial thickness (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7.98\u0026thinsp;\u0026plusmn;\u0026thinsp;1.15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e7.9 (7-8.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e7.86\u0026thinsp;\u0026plusmn;\u0026thinsp;1.06\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e7.5 (7\u0026ndash;8.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.381\u003csup\u003e$\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"6\" nameend=\"c6\" namest=\"c1\"\u003e \u003cp\u003eBMI: Body Mass Index; AFC: Antral Follicle Count; AMH: Anti-M\u0026uuml;llerian Hormone; E\u003csub\u003e2\u003c/sub\u003e: Estrogen; P\u003csub\u003e4\u003c/sub\u003e: Progesterone; M2 oocytes: Metaphase II oocytes (mature eggs); 2PN: fertilized egg with two pronuclei; SD: Standard deviation; IQR: Interquartile range; \u003csup\u003e$\u003c/sup\u003eCalculated by Mann Whitney U test\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec17\" class=\"Section2\"\u003e \u003ch2\u003e3.2. Predictive Analysis of Clinical Pregnancy\u003c/h2\u003e \u003cp\u003eReceiver Operating Characteristic (ROC) curve analysis was conducted to evaluate the predictive value of AFC for clinical pregnancy (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e, Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e). The area under the ROC curve (AUC) was 0.587 (95% CI: 0.513\u0026ndash;0.658, p\u0026thinsp;=\u0026thinsp;0.0399), indicating poor predictive power. The optimal cutoff for AFC was 11, with 88.24% sensitivity but low specificity (28.69%), suggesting that AFC alone is not a strong predictor of clinical pregnancy.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary of the ROC curve for AFC as a predictor of clinical pregnancy\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"2\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eArea\u0026nbsp;under\u0026nbsp;the\u0026nbsp;ROC\u0026nbsp;curve\u0026nbsp;(AUC)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.587\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eStandard\u0026nbsp;Error \u003csup\u003ea\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.0423\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003e95%\u0026nbsp;Confidence\u0026nbsp;interval \u003csup\u003eb\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.513 to 0.658\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003ez\u0026nbsp;statistic\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.054\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSignificance\u0026nbsp;level\u0026nbsp;P\u0026nbsp;(Area\u0026thinsp;=\u0026thinsp;0.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u003cb\u003e0.0399\u003c/b\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eYouden\u0026nbsp;index\u0026nbsp;J\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.1692\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAFC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026gt;\u0026thinsp;11\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSensitivity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e88.24\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSpecificity\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e28.69\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec18\" class=\"Section2\"\u003e \u003ch2\u003e3.3. Binary Logistic Regression Analysis\u003c/h2\u003e \u003cp\u003eA binary logistic regression model (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e) was used to assess the independent effects of significant variables on clinical pregnancy. Key findings include:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eAFC: Higher AFC was associated with increased pregnancy odds (OR\u0026thinsp;=\u0026thinsp;1.027, p\u0026thinsp;=\u0026thinsp;0.038).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eAMH: AMH levels\u0026thinsp;\u0026le;\u0026thinsp;1.2 ng/mL were significantly associated with lower pregnancy likelihood (OR\u0026thinsp;=\u0026thinsp;0.201, p\u0026thinsp;=\u0026thinsp;0.036).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eBlastocyst Transfer: Increased pregnancy odds were observed with blastocyst transfers (OR\u0026thinsp;=\u0026thinsp;1.84, p\u0026thinsp;=\u0026thinsp;0.046).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eEmbryo and Blastocyst Quality: High-quality embryos (OR\u0026thinsp;=\u0026thinsp;3.25, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and high-quality blastocysts (OR\u0026thinsp;=\u0026thinsp;3.79, p\u0026thinsp;=\u0026thinsp;0.004) significantly improved pregnancy rates.\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eNumber of Embryos Transferred:\u003c/p\u003e \u003cp\u003e \u003cul\u003e \u003cli\u003e \u003cp\u003eDouble vs. Single: Higher success with double transfers (OR\u0026thinsp;=\u0026thinsp;5.00, p\u0026thinsp;=\u0026thinsp;0.002).\u003c/p\u003e \u003c/li\u003e \u003cli\u003e \u003cp\u003eTriple vs. Single: Triple transfers also showed increased pregnancy likelihood (OR\u0026thinsp;=\u0026thinsp;3.91, p\u0026thinsp;=\u0026thinsp;0.018).\u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003c/li\u003e \u003c/ul\u003e \u003c/p\u003e \u003cp\u003eThe Hosmer\u0026ndash;Lemeshow goodness-of-fit test indicated an adequate model fit (χ\u0026sup2; = 10.634, p\u0026thinsp;=\u0026thinsp;0.223). The Nagelkerke R\u0026sup2; suggested that embryo quality, blastocyst quality and transfer of two or three embryos vs single embryo had the highest predictive potential for clinical pregnancy.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eSummary table of binary logistic regression\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"7\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c6\" colnum=\"6\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c7\" colnum=\"7\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e \u003cp\u003eVariable\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003e\u0026szlig;\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eSE\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003ep-value\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c5\"\u003e \u003cp\u003eOR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c6\"\u003e \u003cp\u003e95% CI for OR\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c7\"\u003e \u003cp\u003eR\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAFC\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.027\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.013\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.038\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.027\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.001\u0026ndash;1.054\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.031\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAMH\u0026thinsp;\u0026le;\u0026thinsp;1.2ng/ml vs\u0026thinsp;\u0026gt;\u0026thinsp;1.2 ng/ml\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e-1.606\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.766\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.036\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e0.201\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e0.045\u0026ndash;0.901\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.044\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlastocyst transfer\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e0.609\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.305\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.046\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e1.8401\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.01\u0026ndash;3.35\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.028\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eEmbryo quality\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.179\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.338\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u0026lt;\u0026thinsp;0.001\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.25\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.674\u0026ndash;6.309\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.092\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBlastocyst quality\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.335\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.463\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.004\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.79\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.53\u0026ndash;9.41\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.132\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDouble vs single embryos\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.610\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.517\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.002\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e5.003\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.815\u0026ndash;13.793\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eTriple vs single embryos\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e1.364\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.574\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.018\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c5\"\u003e \u003cp\u003e3.91\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c6\"\u003e \u003cp\u003e1.126\u0026ndash;12.055\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c7\"\u003e \u003cp\u003e0.111\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec19\" class=\"Section2\"\u003e \u003ch2\u003e3.4. Multinomial Logistic Regression Analysis\u003c/h2\u003e \u003cp\u003eTo minimise multicollinearity effects, multinomial logistic regression was conducted using the number of embryos transferred, Blastocyst transfer, blastocyst quality, AMH cut-off \u0026le;\u0026thinsp;1.2ng/ml, and AFC. Only embryo quality remained statistically significant (p\u0026thinsp;=\u0026thinsp;0.006), with high-quality embryos increasing pregnancy likelihood nearly fivefold (\u0026szlig;=1.601, SE:0.578; OR\u0026thinsp;=\u0026thinsp;4.96, 95% CI: 1.60\u0026ndash;15.39). The model had a good fit (χ\u0026sup2; = 141.014, p\u0026thinsp;=\u0026thinsp;0.082) with Nagelkerke R\u003csup\u003e\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e\u003c/sup\u003e of 0.241.\u003c/p\u003e \u003c/div\u003e"},{"header":"4. Discussion","content":"\u003cp\u003eIn our study, embryo quality emerged as the most significant factor influencing clinical pregnancy rates (CPR), consistent with numerous studies that highlight the importance of embryo quality in IVF outcomes \u003csup\u003e\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e\u003c/sup\u003e. While various other factors also contribute to IVF success, age remains a well-established predictor. Although our results showed a trend toward higher CPR in women under 35 years (40%) compared to those aged 35 and older (25%), the difference was not statistically significant. This could be due to the small sample size of women\u0026thinsp;\u0026ge;\u0026thinsp;35 years, possibly leading to a type II error. Our findings align with the well-documented decline in ovarian reserve and egg quality beyond 35, which is known to adversely affect IVF success \u003csup\u003e\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAdditionally, the duration of infertility did not show a significant impact on CPR in our study, which is in line with multiple studies suggesting that the length of infertility does not substantially alter pregnancy outcomes, especially when the cause of infertility is not primarily related to ovarian reserve \u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e\u003c/sup\u003e. Body mass index (BMI) has long been implicated in IVF outcomes, with a higher BMI correlating with a reduced likelihood of pregnancy. Our study found that patients with a BMI\u0026thinsp;\u0026lt;\u0026thinsp;25 kg/m\u0026sup2; had a 10% higher CPR than those with BMI\u0026thinsp;\u0026ge;\u0026thinsp;25 kg/m\u0026sup2;, although the difference was not statistically significant. A systematic review by Sermondade et al. confirmed a decrease in live birth probability in individuals with a BMI\u0026thinsp;\u0026ge;\u0026thinsp;30 kg/m\u0026sup2; \u003csup\u003e\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e\u003c/sup\u003e. These findings underscore the need for further investigation into the role of BMI as a modifiable factor in IVF outcomes, particularly given the rising global obesity rates.\u003c/p\u003e \u003cp\u003eOvarian reserve is a critical factor in predicting IVF success. In our study, expected poor responders according to POSEIDON \u003csup\u003e\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e with AFC\u0026thinsp;\u0026le;\u0026thinsp;5 had a CPR of 22%, but the sample size was too small to derive significant conclusions. However, AMH threshold of \u0026le;\u0026thinsp;1.2 ng/ml showed a significant difference in CPR, with a CPR of 11% for AMH\u0026thinsp;\u0026le;\u0026thinsp;1.2 ng/ml and 38% for AMH\u0026thinsp;\u0026gt;\u0026thinsp;1.2 ng/ml [p-value 0.021, OR 4.98 (95% CI 1.1\u0026ndash;22.4)]. This supports the findings of other studies that have demonstrated the utility of AMH as a marker for ovarian reserve, with lower AMH levels being strongly associated with poorer IVF outcomes. A similar study by Esteves et al. found significant differences in cumulative delivery rates between patients with poor versus normal ovarian reserve, further emphasizing the importance of ovarian reserve in predicting pregnancy success \u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe choice of ovarian stimulation protocol is a key aspect of IVF treatment, affecting both the quantity and quality of oocytes retrieved. In our study, most patients underwent stimulation with a flexible antagonist protocol, with a CPR of 38%, which is consistent with the average IVF pregnancy rates. The pregnancy rate for those undergoing stimulation with the agonist protocol was considerably lower at 15.7%, although the small sample size of this subgroup limits the generalizability of this result. The comparison between antagonist and agonist protocols has generated controversial outcomes in various studies \u003csup\u003e\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e,\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe number of mature oocytes retrieved during IVF is a key factor in determining the chances of pregnancy. Our findings showed that patients with fewer than four oocytes had a much lower CPR of 18%, while those with 10\u0026ndash;14 oocytes had a CPR of 45%, and those with more than 15 oocytes had a CPR of 37%. These results align with studies that suggest a higher number of oocytes correlates with better outcomes, although the cumulative live birth rate seems to plateau after a certain point, typically around 15 oocytes \u003csup\u003e\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e\u003c/sup\u003e. In contrast, both lower and excessively high numbers of oocytes are associated with reduced success rates. This finding suggests that targeting an optimal range of oocytes, typically between 5 and 15, may enhance the chances of pregnancy, particularly in the context of FET cycles.\u003c/p\u003e \u003cp\u003eEmbryo quality is perhaps the most critical determinant of IVF success. Our study found a significant difference in CPR between good and poor-quality embryos, with good-quality embryos showing a CPR of 46%, compared to only 18% for poor-quality embryos [p-value\u0026thinsp;\u0026lt;\u0026thinsp;0.001) with OR 3.9 (95% CI 1.98\u0026ndash;7.6)]. This aligns with the body of evidence indicating that top-quality embryos result in significantly higher pregnancy rates \u003csup\u003e\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e\u003c/sup\u003e. Moreover, when comparing blastocyst transfers to cleavage-stage embryo transfers, we observed that blastocyst transfer had a CPR of 44%, significantly higher than the 28% CPR for non-blastocyst transfers. These findings support the literature, which consistently shows that blastocyst transfers offer a better chance of pregnancy, as blastocysts are more likely to implant successfully due to their advanced developmental stage \u003csup\u003e\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eAdditionally, the number of embryos transferred is an important factor. Our study showed that double and triple embryo transfers had significantly higher CPRs (43%) compared to single embryo transfer (13%). While a single embryo transfer carries a lower risk of multiple pregnancies, our results highlight the four to five times higher odds of pregnancy with double and triple embryo transfers. This finding is consistent with the general IVF literature, which suggests that transferring multiple embryos increases the likelihood of pregnancy, albeit with the associated risks of multiple pregnancies \u003csup\u003e\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe role of endometrial factors in IVF success, including endometrial thickness, morphology, and blood flow, has been widely debated. In our study, endometrial thickness did not significantly correlate with clinical pregnancy rates (CPR), although thicker endometrium showed a trend toward slightly improved chances of pregnancy. Other studies, such as one by Shaodi et al., have demonstrated a significant correlation between endometrial thickness and pregnancy rates, especially when the thickness exceeds 8mm \u003csup\u003e\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e\u003c/sup\u003e. Moreover, the presence of a triple-layer endometrial pattern was associated with a 10% higher success rate compared to non-triple-layer patterns, although the difference was not statistically significant in our cohort similar to earlier studies \u003csup\u003e\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e\u003c/sup\u003e. Endometrial blood flow, as assessed by Doppler, showed a 10% higher but non-significant difference in CPR for zone 3 compared to zones 1 and 2, aligning with existing research \u003csup\u003e\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e. Despite trends suggesting endometrial factors impact IVF success, larger studies are needed to confirm their clinical significance in improving outcomes.\u003c/p\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eIn conclusion, while embryo quality remains the most important predictor of IVF success, several other factors\u0026mdash;such as age, ovarian reserve, number and type of embryo transferred\u0026mdash;play significant roles. Endometrial factors, though important, require further investigation to fully elucidate their impact on IVF success. These findings underline the complexity of IVF outcomes and the need for personalized treatment approaches that consider a range of variables to optimize success rates.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eFET- Frozen embryo transfer\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eCPR- Clinical Pregnancy Rate\u003c/p\u003e\n\u003cp\u003eGnRH- Gonadotropin-Releasing Hormone\u003c/p\u003e\n\u003cp\u003eFSH- Follicle Stimulating Hormone\u003c/p\u003e\n\u003cp\u003eLH- Luteinizing Hormone\u003c/p\u003e\n\u003cp\u003eART- Assisted Reproductive Technology\u003c/p\u003e\n\u003cp\u003eBMI- Basal Metabolic Rate\u003cbr\u003e\u0026nbsp;r-FSH- recombinant Follicle Stimulating Hormone\u003c/p\u003e\n\u003cp\u003er-LH- recombinant Luteinizing Hormone\u003c/p\u003e\n\u003cp\u003eHMG- Human Menopausal Gonadotropins\u003c/p\u003e\n\u003cp\u003ehCG- human Chorionic Gonadotropin\u003c/p\u003e\n\u003cp\u003eICSI- Intra-Cytoplasmic Sperm Injection\u003c/p\u003e\n\u003cp\u003eICM- Inner Cell Mass\u003c/p\u003e\n\u003cp\u003eIVF- In-vitro fertilization\u003c/p\u003e\n\u003cp\u003eSD- Standard Deviation\u003c/p\u003e\n\u003cp\u003eIQR- Interquartile Range\u003c/p\u003e\n\u003cp\u003eROC- Receiver Operating Curve\u003c/p\u003e\n\u003cp\u003eAMH- Anti-M\u0026uuml;llerian hormone\u003c/p\u003e\n\u003cp\u003eAFC- Antral Follicle Count\u003c/p\u003e\n\u003cp\u003eM2- Metaphase II\u003c/p\u003e\n\u003cp\u003eSSR- Surgical Sperm Retrieval\u003c/p\u003e\n\u003cp\u003ePCOS- Polycystic Ovary Syndrome\u003c/p\u003e\n\u003cp\u003eOAT- Oligoasthenoteratozoospermia\u003c/p\u003e\n\u003cp\u003e2PN- Two Pronuclei\u003c/p\u003e\n\u003cp\u003ePOSEIDON- Patient-Oriented Strategies Encompassing Individualized Oocyte\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe study protocol was approved by the Institutional Review Committee (IRC), and Human Ethics Committee (HEC) of Government Medical College, Thiruvananthapuram vide letter no: HEC.No.04/92/2020/MCT dated 26/06/2020. Written informed consent was obtained from participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed consent for publication was provided by the participants.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and material\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and/or analysed during the current study are available in the Mendeley data repository, DOI: 10.17632/hp9n9w6w2f.1\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that there is no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003cstrong\u003e\u0026nbsp;Funding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone received\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eSA- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eSB- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eDR- conceptualization, investigation, methodology, formal analysis, project administration, visualisation, supervision, writing original draft, writing- review and editing.\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNone\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eTrounson A, Mohr L. Human pregnancy following cryopreservation, thawing and transfer of an eight-cell embryo. \u003cem\u003eNature\u003c/em\u003e. 1983;305(5936):707-709. doi:10.1038/305707a0\u003c/li\u003e\n\u003cli\u003eTiitinen A. Elective single embryo transfer: the value of cryopreservation. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2001;16(6):1140-1144. doi:10.1093/humrep/16.6.1140\u003c/li\u003e\n\u003cli\u003eAshrafi M, Jahangiri N, Hassani F, Akhoond MR, Madani T. The factors affecting the outcome of frozen\u0026ndash;thawed embryo transfer cycle. \u003cem\u003eTaiwanese Journal of Obstetrics and Gynecology\u003c/em\u003e. 2011;50(2):159-164. doi:10.1016/j.tjog.2011.01.037\u003c/li\u003e\n\u003cli\u003eEftekhar M, Rahmani E, Pourmasumi S. Evaluation of clinical factors influencing pregnancy rate in frozen embryo transfer. \u003cem\u003eIran J Reprod Med\u003c/em\u003e. 2014;12(7):513-518.\u003c/li\u003e\n\u003cli\u003eVeleva Z, Orava M, Nuojua-Huttunen S, Tapanainen JS, Martikainen H. Factors affecting the outcome of frozen-thawed embryo transfer. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2013;28(9):2425-2431. doi:10.1093/humrep/det251\u003c/li\u003e\n\u003cli\u003eHuang TTF. The kitazato \u0026ldquo;closed\u0026rdquo; cryotop sc vitrification system performs comparably to its original \u0026ldquo;open\u0026rdquo; system. a study using unfertilized human eggs, mouse eggs, and mouse embryos. \u003cem\u003eFertility and Sterility\u003c/em\u003e. 2016;105(2):e22-e23. doi:10.1016/j.fertnstert.2015.12.072\u003c/li\u003e\n\u003cli\u003eApplebaum M. The uterine biophysical profile. \u003cem\u003eUltrasound in Obstet \u0026amp; Gyne\u003c/em\u003e. 1995;5(1):67-68. doi:10.1046/j.1469-0705.1995.05010067.x\u003c/li\u003e\n\u003cli\u003eAlpha Scientists in Reproductive Medicine and ESHRE Special Interest Group of Embryology, Balaban B, Brison D, et al. The Istanbul consensus workshop on embryo assessment: proceedings of an expert meeting. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2011;26(6):1270-1283. doi:10.1093/humrep/der037\u003c/li\u003e\n\u003cli\u003eGardner DK, Schoolcraft WB. Culture and transfer of human blastocysts: \u003cem\u003eCurrent Opinion in Obstetrics and Gynaecology\u003c/em\u003e. 1999;11(3):307-311. doi:10.1097/00001703-199906000-00013\u003c/li\u003e\n\u003cli\u003eAcharya S, Balakrishnan S, Rath D. Pregnancy Rates After Frozen Embryo Transfer: Insights from an Indian Government Hospital. \u003cem\u003eIJMRGE\u003c/em\u003e. 2025;6(2):965-972. doi:10.54660/.IJMRGE.2025.6.2.965-972\u003c/li\u003e\n\u003cli\u003eOron G, Son WY, Buckett W, Tulandi T, Holzer H. The association between embryo quality and perinatal outcome of singletons born after single embryo transfers: a pilot study. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2014;29(7):1444-1451. doi:10.1093/humrep/deu079\u003c/li\u003e\n\u003cli\u003eSun YF, Zhang J, Xu YM, et al. Effects of age on pregnancy outcomes in patients with simple tubal factor infertility receiving frozen-thawed embryo transfer. \u003cem\u003eSci Rep\u003c/em\u003e. 2020;10(1):18121. doi:10.1038/s41598-020-75124-3\u003c/li\u003e\n\u003cli\u003eSermondade N, Huberlant S, Bourhis-Lefebvre V, et al. Female obesity is negatively associated with live birth rate following IVF: a systematic review and meta-analysis. \u003cem\u003eHuman Reproduction Update\u003c/em\u003e. 2019;25(4):439-451. doi:10.1093/humupd/dmz011\u003c/li\u003e\n\u003cli\u003eGrisendi V, Mastellari E, La Marca A. Ovarian Reserve Markers to Identify Poor Responders in the Context of Poseidon Classification. \u003cem\u003eFront Endocrinol\u003c/em\u003e. 2019;10:281. doi:10.3389/fendo.2019.00281\u003c/li\u003e\n\u003cli\u003eEsteves SC, Yarali H, Vuong LN, et al. Cumulative delivery rate per aspiration IVF/ICSI cycle in POSEIDON patients: a real-world evidence study of 9073 patients. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2021;36(8):2157-2169. doi:10.1093/humrep/deab152\u003c/li\u003e\n\u003cli\u003eLai Q, Zhang H, Zhu G, et al. Comparison of the GnRH agonist and antagonist protocol on the same patients in assisted reproduction during controlled ovarian stimulation cycles. \u003cem\u003eInt J Clin Exp Pathol\u003c/em\u003e. 2013;6(9):1903-1910.\u003c/li\u003e\n\u003cli\u003eAl-Mousawi BJ, Al-Azzam MAH, Al-Zahawi B, Fawzi HA. Agonist Versus Antagonist in Intracytoplasmic Sperm Injection Cycles: Which Is the Best? \u003cem\u003eInternational Journal of Women\u0026rsquo;s Health and Reproduction Sciences\u003c/em\u003e. 2019;8(3):285-289. doi:10.15296/ijwhr.2020.46\u003c/li\u003e\n\u003cli\u003eTimeva T, Milachich T, Antonova I, Arabaji T, Shterev A, Omar HA. Correlation Between Number of Retrieved Oocytes and Pregnancy Rate After \u003cem\u003eIn Vitro\u003c/em\u003e Fertilization/IntraCytoplasmic Sperm Infection. \u003cem\u003eThe Scientific World JOURNAL\u003c/em\u003e. 2006;6:686-690. doi:10.1100/tsw.2006.145\u003c/li\u003e\n\u003cli\u003eDe Neubourg D. Single top quality embryo transfer as a model for prediction of early pregnancy outcome. \u003cem\u003eHuman Reproduction\u003c/em\u003e. 2004;19(6):1476-1479. doi:10.1093/humrep/deh283\u003c/li\u003e\n\u003cli\u003eGardner DK, Lane M, Stevens J, Schlenker T, Schoolcraft WB. Blastocyst score affects implantation and pregnancy outcome: towards a single blastocyst transfer. \u003cem\u003eFertility and Sterility\u003c/em\u003e. 2000;73(6):1155-1158. doi:10.1016/S0015-0282(00)00518-5\u003c/li\u003e\n\u003cli\u003eThurin A, Hausken J, Hillensj\u0026ouml; T, et al. Elective Single-Embryo Transfer versus Double-Embryo Transfer in in Vitro Fertilization. \u003cem\u003eN Engl J Med\u003c/em\u003e. 2004;351(23):2392-2402. doi:10.1056/NEJMoa041032\u003c/li\u003e\n\u003cli\u003eShaodi Z, Qiuyuan L, Yisha Y, Cuilian Z. The effect of endometrial thickness on pregnancy outcomes of frozen-thawed embryo transfer cycles which underwent hormone replacement therapy. Yu Y, ed. \u003cem\u003ePLoS ONE\u003c/em\u003e. 2020;15(9):e0239120. doi:10.1371/journal.pone.0239120\u003c/li\u003e\n\u003cli\u003eYang W, Zhang T, Li Z, et al. Combined analysis of endometrial thickness and pattern in predicting clinical outcomes of frozen embryo transfer cycles with morphological good-quality blastocyst: A retrospective cohort study. \u003cem\u003eMedicine\u003c/em\u003e. 2018;97(2):e9577. doi:10.1097/MD.0000000000009577\u003c/li\u003e\n\u003cli\u003eChien LW, Au HK, Chen PL, Xiao J, Tzeng CR. Assessment of uterine receptivity by the endometrial-subendometrial blood flow distribution pattern in women undergoing in vitro fertilization-embryo transfer. \u003cem\u003eFertility and Sterility\u003c/em\u003e. 2002;78(2):245-251. doi:10.1016/S0015-0282(02)03223-5\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"middle-east-fertility-society-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mefj","sideBox":"Learn more about [High Temperature Corrosion of Materials](https://www.springer.com/journal/43043)","snPcode":"43043","submissionUrl":"https://submission.nature.com/new-submission/43043/3","title":"Middle East Fertility Society Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Clinical pregnancy rate, embryo, endometrium, Anti-Müllerian hormone, Antral Follicle Count, Blastocyst","lastPublishedDoi":"10.21203/rs.3.rs-6384128/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6384128/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eThis study aims to identify factors influencing the outcomes of frozen embryo transfer (FET) cycles.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA prospective observational study was conducted on participants who underwent FET of autologous embryos after endometrial preparation with hormone therapy. Patient characteristics, ovarian stimulation details, and embryo specifics were recorded. Endometrial thickness, morphology, and Doppler flow were assessed on the day of progesterone start. Embryo details on the transfer day were also recorded. Serum \u0026szlig;-hCG levels were measured twelve days post-transfer, and those with levels\u0026thinsp;\u0026gt;\u0026thinsp;25 IU/L underwent a 6-week ultrasound to detect a gestational sac. The clinical pregnancy rate (CPR) was calculated, and statistical differences between pregnant and non-pregnant groups were evaluated using Chi-square or Fisher\u0026rsquo;s exact tests for categorical variables and the Mann-Whitney U-test for continuous variables. Logistic regression analysis was used to identify independent variables associated with successful pregnancy outcomes.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eFor a total of 190 cycles, the CPR was 35.7%. Univariate logistic regression revealed that antral follicle count (AFC), Anti-M\u0026uuml;llerian hormone (AMH), blastocyst transfer, embryo quality, and transferring more than one embryo were significantly associated with CPR. On multivariate analysis, embryo quality remained the only independent predictor of successful FET outcomes.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eEmbryo quality is the most significant predictor of successful FET outcomes. Other factors like age, ovarian reserve, number and type of embryo transferred also influence success, further research is needed to understand the role of endometrial factors. Tailored treatment approaches are crucial for optimising IVF success.\u003c/p\u003e","manuscriptTitle":"Factors Affecting Frozen Embryo Transfer Success Rates","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-04-09 08:29:34","doi":"10.21203/rs.3.rs-6384128/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-09-14T10:01:58+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-11T16:19:26+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-11T03:02:27+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"288413880679753420478843039344015158794","date":"2025-09-09T12:45:02+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"198419806223534152249103004001940378880","date":"2025-09-08T09:33:36+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-09-02T11:37:17+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-08-30T08:00:46+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"146423649421475291358597431798125137356","date":"2025-08-15T02:59:30+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"81347281316617316076024131617141755342","date":"2025-08-14T11:02:48+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-08-02T07:31:54+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-04-19T18:17:28+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-04-07T09:51:21+00:00","index":"","fulltext":""},{"type":"submitted","content":"Middle East Fertility Society Journal","date":"2025-04-05T23:42:52+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"middle-east-fertility-society-journal","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"mefj","sideBox":"Learn more about [High Temperature Corrosion of Materials](https://www.springer.com/journal/43043)","snPcode":"43043","submissionUrl":"https://submission.nature.com/new-submission/43043/3","title":"Middle East Fertility Society Journal","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"Springer Open","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"25024a1a-ebc3-4dc6-bc71-149dd6c6ae35","owner":[],"postedDate":"April 9th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-10-27T16:27:47+00:00","versionOfRecord":{"articleIdentity":"rs-6384128","link":"https://doi.org/10.1186/s43043-025-00263-4","journal":{"identity":"middle-east-fertility-society-journal","isVorOnly":false,"title":"Middle East Fertility Society Journal"},"publishedOn":"2025-10-25 16:17:05","publishedOnDateReadable":"October 25th, 2025"},"versionCreatedAt":"2025-04-09 08:29:34","video":"","vorDoi":"10.1186/s43043-025-00263-4","vorDoiUrl":"https://doi.org/10.1186/s43043-025-00263-4","workflowStages":[]},"version":"v1","identity":"rs-6384128","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6384128","identity":"rs-6384128","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}