What is the Optimal Number of Embryos to Transfer for Poseidon Group 1 and Group 2? A retrospective study

What is the Optimal Number of Embryos to Transfer for Poseidon Group 1 and Group 2? 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A retrospective study Rang Liu, Qiuju Zhang, Lan Geng, Huiqing He, Chang Xu, Jiali Feng, and 4 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-2752135/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background: The 2016 Patient-Oriented Strategy Encompassing IndividualizeD Oocyte Number (POSEIDON) criteria redefined the poor responders as low prognosis patients. The embryo transfer strategy for Poseidon patients remained to be addressed. This study aimed to investigate the optimized number of embryos to transfer for unexpected low-prognosis patients (Poseidon Group 1 and Group 2) with blastocyst transfer in their first frozen cycle. Methods: A retrospective cohort study of 2970 patients who underwent frozen-thawed embryo transfer (FET) between January 2018 and December 2021. Patients from Poseidon Group 1 (N=219) and Group 2 (N=135) who underwent blastocyst transfer in their first FET cycles were included and divided into the elective single embryo transfer (eSET) group and the double embryo transfer (DET) group. Results: For Poseidon Group 1, the live birth rateper embryo transfer of the DET group was slightly higher than the eSET group (52.17% vs 46.15%, OR 0.786, 95% CI 0.462-1.337, P = 0.374; adjusted OR (aOR) 0.622, 95% CI 0.340-1.140, P = 0.124), while a significant increase of 20.00% in the multiple birth rate was shown. For Group 2, higher live birth rates were observed in the DET group compared to the eSET group (38.46% vs 20.48%, OR 0.412, 95% CI 0.190-0.892, P = 0.024; aOR 0.358, 95% CI 0.155-0.828, P = 0.016). The difference in the multiple birth rate was 20.00% without statistical significance. Univariate and multivariate analyses revealed that age (OR 0.759, 95% CI .624-0.922, P = 0.006 and OR 0.751, 95% CI 0.605-0.932, P = 0.009) and the number of transferred embryos (OR 0.412, 95% CI 0.190-0.892, P = 0.024 and OR 0.367, 95% CI 0.161-0.840, P = 0.018) were significant variables for the live birth rate in Poseidon Group 2. Conclusions: The findings in the present study showed that eSET was preferred in the first frozen cycle for Poseidon Group 1 to avoid unnecessary risks. Double embryo transfer strategy could be considered to improve the success rate for Poseidon Group 2 with caution. Further stratification by age is needed for a more scientific discussion about the embryo transfer strategy for Poseidon patients. embryo transfer strategy Poseidon criteria low prognosis live birth rate multiple birth rate Figures Figure 1 Figure 2 Introduction Despite the spectacular development and fruitful achievement, assisted reproductive technology (ART) has not yet perfectly satisfied every patient. Patients with diminished ovarian reserve (DOR) or poor ovarian response (POR) are considered one of the most difficult populations for their frustrating outcomes even after ART treatment, making their management a thorny issue for reproductive clinicians [ 1 ]. To address the heterogeneity in the definition, in 2011 the European Society of Human Reproduction and Embryology (ESHRE) standardized poor responders by the Bologna criteria [ 2 ]. It was pointed out that the Bologna criteria might not be practical or efficient enough to manage patients since heterogeneity of treatment strategy remained after categorization. The 2016 Patient-Oriented Strategy Encompassing IndividualizeD Oocyte Number (POSEIDON) group more detailly stratified the poor responders into 4 groups by age, ovarian biomarkers, and the number of oocytes retrieved, transiting the definition of POR to the concept of low prognosis. Under the new criteria, patients are further classified as unexpected low-prognosis if they presented a favorable ovarian reserve test (antral follicle count (AFC) ≥ 5 or/and anti-mullerian hormone (AMH) ≥ 1.2 ng/ml) but with a low response in a standard ovarian stimulation cycle (≤ 9 oocytes), and as expected low-prognosis if low ovarian reserve were shown [ 3 ]. Although Poseidon stratification ameliorates the difficulties in counseling and prognosis prediction, it continued to challenge experts that how to manage these low-prognosis patients in each node of ART treatment to optimize the outcomes. Scholars have intensely discussed the pretreatment, adjuvant treatment, ovarian stimulation protocols, and maximization of oocyte or embryo usability by laboratory techniques [ 1 ]. Up to the present, research has yet to pay much attention to the embryo transfer strategy for low-prognosis patients under the Poseidon classification, which is a question eventually inevitable to be answered. As assisted conception technologies progressed, high-quality success was more and more pursued rather than just obtaining live births. Ideally, successful in vitro fertilization (IVF) treatment was expected to result in one healthy singleton by an optimal embryo transfer strategy. However, in order to improve the prognosis of unfavorable patients, the transfer of more than one embryo would be considered, which was also out of the wishes for reducing unnecessary multiple transfers and relieving the patient’s anxiety. Unfortunately, patients were exposed to the potential risk of multiple births. While maintaining a satisfactory delivery rate, multiple births should be controlled by various strategies to reduce complications, including adverse maternal and neonatal outcomes [ 4 ]. Early in the end of 20th century, elective single embryo transfer (eSET) was recommended to mitigate the risk of multiple births [ 5 ]. The 2013 American Society for Reproductive Medicine and Society for Assisted Reproductive Technology (ASRM/SART) committee opinion suggested young patients with favorable prognoses be transferred 1–2 cleavage-stage embryos or single blastocyst [ 6 ]. Further defining the concept of “favorable” in detail, the 2021 ASRM/SART committee opinion recommended single embryo transfer for patients ≤ 37 years with favorable prognoses, and that increased embryo number by age or if the embryo was not euploid or favorable [ 7 ]. Since 42%-45% of favorable prognosis patients in the US did not undergo eSET, leading to an unacceptable multiple birth rate, it was recently proposed to enhance adherence to the guideline [ 8 , 9 ]. Paradoxical as it may seem, patients classified as low prognosis by Poseidon criteria undergoing blastocyst transfer in their first frozen embryo transfer cycle (FET) were associated with a favorable prognosis according to the 2021 ASRM/SART committee opinion [ 7 ]. The appropriate number of embryos to transfer for this patient population remains to be addressed. Thus, the aim of this article was to investigate the optimized number of transferred embryos to improve the prognosis of unexpected low-prognosis patients by comparing the clinical outcomes of different blastocyst transfer protocols in the first FET among Poseidon Groups 1 and 2. Materials And Methods Patient Selection This was a retrospective study conducted among patients who underwent ART treatment at the Peking University Shenzhen Hospital Reproductive Medicine Center between January 2018 and December 2021. 2970 patients fulfilling the POSEIDON criteria who underwent FET cycles were sorted out and classified accordingly [3]. Group 1: Patients <35 years with AFC ≥5 and/or AMH ≥1.2 ng/mL and with an unexpected poor or suboptimal ovarian response (retrieved ≤9 oocytes). Group 2: Patients ≥35 years with AFC ≥5 and/or AMH ≥1.2 ng/mL and with an unexpected poor or suboptimal ovarian response. As reported in a previous study, AMH and AFC had equivalent accuracy and efficacy for patient stratification [10]. In our study, AMH rather than AFC was used for grouping since it was more objective with less potential bias. Oocyte retrieval in Group 1 or Group 2 was conducted under standard ovarian stimulation. Patients classified to Poseidon Group 3 and Group 4, who underwent preimplantation genetic screening/diagnosis (PGS/PGD), who were with previous fresh embryo transfers or FET history were excluded. Patients with only one cryopreserved embryo at the time of transfer were also eliminated. Only patients from Group 1 and Group 2 with blastocysts transferred in their first FET cycle and had completed the follow-up were included for analysis. Outcome follow-ups were conducted offline when patients returned to the center or online by telephone. Based on the number of blastocysts to transfer, patients were further divided into subgroups including elective single embryo transfer (e-SET) and double embryo transfer (DET) (Figure I). Ovarian Stimulation Standard ovarian stimulation protocols including gonadotrophin-releasing hormone (GnRH) antagonist and GnRH agonist (ultra-long/long) were used individually [11-13]. Based on ovarian reserve, age, body mass index (BMI), and previous stimulation outcome if available, patients received subcutaneous injections of recombinant gonadotropin (recombinant FSH (GONAL-f, Merck Serono, Germany) /purified hMG (Urofollitropin, Livzon Pharmaceuticals, China) /recombinant FSH plus hMG or recombinant LH (Luveris, Merck Serono, Germany), 2:1 ratio) with an initial daily dosage of 150-450IU. GnRH-antagonist (Cetrotide, Merck Serono, Germany or Ganirelix, MSD, USA) was administered starting from the day when the dominant follicle reached 12-14 mm in diameter until the trigger day. GnRH-agonist (Decapeptyl, Ferring pharmaceuticals, Switzerland) was initiated prior to ovarian stimulation with one to three injections to achieve downregulation in the ultra-long protocol or from the previous mid-luteal phase in the long protocol. Recombinant HCG (Choriogonadotropin alfa, Merck Serono, Germany) or recombinant HCG combined with GnRH agonist was applied to trigger the final maturation when at least two lead follicles reached greater than 18 mm in diameter. Oocyte retrieval was conducted 36-38 hours after triggering. Outcomes The primary outcomes were the live birth rate, defined as the rate of patients giving birth to a fetus of any living sign after 28 weeks of gestation, and the multiple birth rate, defined as the rate of giving birth to more than one living infant among all live births. The secondary outcomes included (i) biochemical pregnancy rate defined as the rate of patients with positive detection of urine or serum beta-HCG test, (ii) clinical pregnancy rate, defined as the rate of patients with pregnancy diagnosed by ultrasonographic confirmation of intrauterine gestational sac 28 days after embryo transfer, (iii) ongoing pregnancy rate, defined as the rate of patient with ultrasonographic confirmation of intrauterine fetal heart activity beyond 12 weeks of gestation. Statistics All the statistical analysis was performed by SPSS statistics version 26.0 (IBM, Armonk, NY, USA). Continuous data were expressed as mean ± SD and compared by Student’s t-test. Categorical data were presented as frequencies and percentages. The Chi-square test or Fisher’s exact test was used to compare rates in the baseline characteristics. Logistic regression analysis was applied to output the unadjusted odds ratio (OR) and the adjusted OR (aOR) with 95% CI for the rates of outcomes. Potential confounding variables were adjusted including age, BMI, indications for IVF, AFC, endometrium thickness (EMT) on the day of transfer, and the number of oocytes retrieved. Finally, univariate and multivariate analyses were performed to analyze the associated variables for live birth rates and the results were reported as OR with 95% CI. A two-sided P value <0.05 was considered statistically significant. Results Baseline Clinical Characteristics In this study, a total of 354 frozen blastocyst transfer cycles from Poseidon Group 1 (N = 219) and Group 2 (N = 135) were analyzed. Supplementary Table 1 summarized general patient characteristics. Compared to Poseidon Group 1, Group 2 had significantly higher age (37.87±2.52 versus 30.68±2.70, P = 0.000), lower AFC (9.95±4.65 versus 12.01±5.13, P = 0.000), lower AMH (3.00±2.32 versus 3.77±2.25, P = 0.002) and higher total gonadotropin (Gn) dose (2980.56±1161.65 versus 2454.37±1028.87, P = 0.000). Basal hormonal level (except LH), controlled ovarian hyperstimulation (COH) protocol, and the number of oocytes retrieved were comparable between Group 1 and Group 2. Indications for IVF ( P = 0.028) and BMI (22.14±2.53 versus 21.18±3.02, P = 0.002) were significantly different between groups. The number of patients/cycles transferring one embryo and transferring two embryos was 104 versus 115 in Poseidon Group 1 and 83 versus 52 in Group 2, respectively. The baseline characteristics of subgroups were summarized in Table 1. Significant differences existed in comparison of indications for IVF ( P = 0.001), AFC (11.20±4.95 versus 12.74±5.21, P = 0.027), and number of oocytes retrieved (6.25±2.18 versus 7.03±1.89, P = 0.005), EMT on the day of transfer (11.54±2.26 versus 10.89±2.28, P = 0.037) between eSET and DET in Group 1. All indicators were comparable between eSET and DET within Group 2. Clinical Outcomes For Poseidon Group 1, the live birth rate per embryo transfer was 46.15% in the eSET group and 52.17% in the DET group (OR 0.786, 95% CI 0.462-1.337, P = 0.374; aOR 0.622, 95% CI 0.340-1.140, P = 0.124). However, a multiple birth rate of 20.00% was shown in the DET group ( P = 0.001) (Table 2, Figure 2). Similarly, biochemical pregnancy rate, clinical pregnancy rate and ongoing pregnancy rate increased from 62.50% to 64.35% (OR 0. 923, 95% CI 0.532-1.602, P = 0.777; aOR 0.663, 95% CI 0.354-1.241, P = 0.199), 56.73% to 61.74% (OR 0.813, 95% CI 0.473-1.395, P = 0.451; aOR 0.585, 95% CI 0.315-1.089, P = 0.091), and 48.08% to 55.65% (OR 0.738, 95% CI 0.433-1.256, P = 0.263; aOR 0.614, 95% CI 0.335-1.123, P = 0.113) without statistically significant differences when comparing the eSET group to the DET group (Table 2). The live birth rate in the eSET group was significantly different from that in the DET group (20.48% versus 38.46%, OR 0.412, 95% CI 0.190-0.892, P = 0.024; aOR 0.358, 95% CI 0.155-0.828, P = 0.016) in Poseidon Group 2. The multiple birth rate increased to 20.00% in the DET group without significance compared to the eSET group ( P = 0.155) (Table 2, Figure 2). The value for the ongoing pregnancy rate was in accord with the live birth rate. Biochemical and clinical pregnancy rates increased from 36.14% to 55.77% (OR 0.499, 95% CI 0.221-0.910, P = 0.026; aOR 0.409, 95% CI 0.189-0.888, P = 0.024) and 33.73% to 50.00% (OR 0.509, 95% CI 0.251-1.034, P = 0.062; aOR 0.473, 95% CI 0.219-1.019, P = 0.056) comparing the eSET group to the DET group (Table 2). Among the potential associated variables on the live birth rate, including age, BMI, AFC, EMT, the number of oocytes retrieved, and the number of transferred embryos, univariate and multivariate analyses showed that in Poseidon Group 1, none of the above variables was found to be significantly associated with the live birth rate. However, for Group 2, age (OR 0.759, 95% CI 0.624-0.922, P = 0.006 and OR 0.751, 95% CI 0.605-0.932, P = 0.009) and the number of transferred (OR 0.412, 95% CI 0.190-0.892, P = 0.024 and OR 0.367, 95% CI 0.161-0.840, P = 0.018) embryos were shown to have a significant association with the live birth rate (Table 3). Discussion To the best of our knowledge, there was a lack of the discussion about the management of Poseidon low-prognosis patients specific to the embryo transfer protocols, including the decisions on embryo quantity and quality. Our study showed the novelty that the embryo number to transfer for the Poseidon Group was focused on for the first time. The current study analyzed the first FET with blastocyst transfer, and it was observed in Poseidon Group 1 that compared to single blastocyst transfer, an upward trend was present among the clinical outcomes of double blastocyst transfer but without significance, which was accompanied by a significant increase of multiple birth rate. In Poseidon Group 2, double blastocyst transfer was significantly associated with the improvement in clinical outcomes with multiple birth rate not significantly increased. Furthermore, age and the number of transferred embryos were demonstrated to be crucial variables for the live birth rate in unexpected low-prognosis patients ≥ 35 years. Embryo transfer strategy, as the most crucial part of controlling multiple births, has been constantly discussed in different patient populations. Focusing on poor responders, an early study found double embryo transfer might lead to a higher live birth rate than those with single embryo transfer, with a modest increase in the multiple birth rate (9.1%) [ 14 ]. In 2015, Gleicher et al retrospectively analyzed the live birth rates of transferring embryos in various numbers among poor responders by Bologna criteria. With age stratification, the results showed that young patients had a satisfactory live birth rate of 33% whether with non-elective one or two embryos transferred. Live birth rates in patients aged 35–37 and 38–40 seemed to associate with embryo number. For patients with advanced age, the rates were as low as 5.9%-7.4% even after three embryos were transferred [ 15 ]. Patient prognosis was considered one of the critical factors for the decisions on transfer protocols. Various studies investigated embryo transfer strategies for patients with different prognoses. However, the standard of prognosis was not consistently defined in these studies. Loendersloot et al. defined women ≤ 35 years who underwent their first IVF/ICSI cycle as good prognosis and women ≥ 39 years as poor prognosis. Women aged between 35–39 years, young patients undergoing their first IVF without a top-quality embryo, or having at least one failed IVF cycle were classified as intermediate prognosis [ 16 ]. Another study classified patients’ prognoses according to their previous IVF history and outcomes, as well as whether they had extra embryos for cryopreservation [ 17 ]. Gleicher et al. defined poor responders under Bologna criteria as a very poor prognosis population [ 15 ]. Since 2016, Poseidon criteria have converted the conception of poor responder into low prognosis. Our study provided a novel comparative analysis under the Poseidon low prognosis conception and the favorable clinical setting according to the 2021 ASRM/SART guideline. In our study, Poseidon Group 1 did not obviously benefit from double blastocysts transfer, which was associated with a slight increase of 6.02% in the live birth rate. However, the benefits were largely offset by the multiple birth rates significantly rising to 20.00% (Table 2, Fig. 2 ). It was worth mentioning that the live birth rate could reach 46.15% with elective single blastocyst transfer. Similar to the study by Gleicher et al [ 15 ], although defined as low prognosis by Poseidon criteria, patients aged ≤ 35 years seemed to have quite satisfying outcomes. A previous study reported that the blastulation rate of embryos and the live birth rates per embryo transfer cycle in young patients with low ovarian response were equivalent to those with a normal response, indicating that oocyte quality may not decline in this population [ 18 ]. It was demonstrated in a more recent study that euploidy rates in Poseidon Group 1 were not significantly different from good-prognosis patients and were not influenced by the ovarian response [ 19 ]. This information may give a hint about the embryo accumulation protocol. Moreover, Poseidon Group 1, as the young unexpected low-prognosis patients, possibly could be regarded as good prognosis once they underwent blastocyst transfer in the first FET. Given that acceptable outcomes were observed in eSET and multiple birth rates raised in DET, this patient population should be encouraged to adopt single embryo transfer, as the 2021 ASRM/SART embryo transfer guideline recommended [ 7 ]. Our study demonstrated a significant association between embryo number and clinical outcomes in Poseidon Group 2. Double blastocyst transfer showed its superiority in promoting the live birth rate from 20.48–38.46%. Logistic regression analysis suggested both age and embryo number as important variables in this group. Heterogeneity remained in the efficiency of different embryo transfer strategies for aged patients in the previous clinical research. A retrospective analysis including 155 patients with ages ≥ 35 years reported that the live birth rate of double blastocyst transfer did not differ from single blastocyst transfer (46.5% versus 37.0%, P = 0.228), whereas the risks of preterm birth and low birth weight increased [ 20 ]. Another retrospective cohort for patients ≥ 40 years demonstrated that compared to elective single blastocyst transfer, double blastocyst transfer showed a similar live birth rate (22.8% versus 20%, P = 0.20). However, elective double blastocyst transfer, which meant extra blastocyst available for cryopreservation, achieved significant improvement in the live birth rate (30.6% versus 20%, P = 0.017) [ 21 ]. The study targeting patients aged 40–44 years by Niinimäki, M et al. showed the opposite result that advanced patients had higher cumulative live birth rates with elective single embryo transfer than with double embryo transfer (22.7% versus 13.2%, P = 0.002) [ 22 ]. These studies did not further stratify the patients according to their prognosis, which was an important consideration for making a transfer strategy. For Poseidon Group 2, it seemed that double embryo transfer would be preferred when merely discussing the live birth rate. Meanwhile, the potential accompanying risk of multiple births should be noticed. With the restriction of local policies, cases of transferring more than two blastocysts were lacking. It is expected that data about clinical outcomes with multiple embryo transfers for Poseidon patients could be discussed worldwide in the future. We also observed that many studies about embryo transfer refined the patients’ age when discussing the aged population, and Logistic regression demonstrated the significance of age for the live birth rate. It may inspire us to further stratify the patients’ age in the following study to test the results in each refining age group. Our study was also limited in the nature of the retrospective design with inherent bias and unknown confounders. Another limitation was that only Poseidon Group 1 and Group 2 were included in the present study given that clinical data of Poseidon Group 3 and Group 4 were relatively fewer for analysis and collecting work was still ongoing. A large-scale multi-center prospective analysis is expected to further investigate the embryo transfer strategy for Poseidon patients. In conclusion, following the embryo transfer guideline, we advocated single blastocyst transfer as the first option in the first FET cycle for Poseidon Group 1. Poseidon Group 2 could benefit from double embryo transfer. When multiple embryo transfer was selected, the risk of multiple birth rates should be considered and personal willingness, basic health conditions as well as economic factors should be fully evaluated. A more scientific discussion about the embryo transfer strategy under Poseidon criteria might base on a reasonable age stratification. More precise management based on Poseidon criteria may be the treatment strategy for poor responders in the future. Abbreviations eSET=elective single embryo transfer; DET=double embryo transfer; ART=assisted reproductive technology; DOR=diminished ovarian reserve; POR=poor ovarian response; AFC=antral follicle count; AMH= anti-mullerian hormone ; IVF=in vitro fertilization; FET= frozen embryo transfer; PGS/PGD=preimplantation genetic screening/diagnosis; ICM=inner cell mass; TE=trophectoderm; BMI=body mass index; EMT=endometrium thickness; Gn=gonadotropin; COH=controlled ovarian hyperstimulation Declarations Ethics approval and consent to participate Ethics approval was obtained from the committee of Peking University Shenzhen Hospital without the need for informed consent. Consent for publication Not applicable. Data Availability Statements The data underlying this article will be shared on reasonable request to the corresponding author. Competing interests The authors declare no competing interests. Funding This work was supported by the Shenzhen Fundamental Research Program (JCYJ20200109150429414). Authors’ contributions R.L. – Manuscript Drafting and Data Analysis; Q.Z. – Review and Editing; R.L., Q.Z. and X.X. – Study Design; L.G., H.H. – Data Verification; J.F., M.S. and Y.C. – Data Collection; C.X. – Statistical Tutoring; T.W. and X.X. – Conceptualization, Critical Discussion and Supervision. All authors reviewed the manuscript. Acknowledgments We thank all the staff in the center for reproductive medicine of Peking University Shenzhen hospital and all the patients who underwent ART treatment at our center. References Cedars MI. Managing poor ovarian response in the patient with diminished ovarian reserve. Fertil Steril. 2022;117(4):655-6. Ferraretti AP, La Marca A, Fauser BCJM, Tarlatzis B, Nargund G, Gianaroli L. ESHRE consensus on the definition of 'poor response' to ovarian stimulation for in vitro fertilization: the Bologna criteria. Hum Reprod. 2011;26(7):1616-24. 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Live-birth rates in very poor prognosis patients, who are defined as poor responders under the Bologna criteria, with nonelective single embryo, two-embryo, and three or more embryos transferred. Fertil Steril. 2015;104(6):1435-41. van Loendersloot L, van Wely M, Goddijn M, Repping S, Bossuyt P, van der Veen F. Pregnancy and twinning rates using a tailored embryo transfer policy. Reprod Biomed Online. 2013;26(5):462-9. Kissin DM, Kulkarni AD, Kushnir VA, Jamieson DJ. Number of embryos transferred after in vitro fertilization and good perinatal outcome. Obstet Gynecol. 2014;123(2 Pt 1):239-47. Morin SJ, Patounakis G, Juneau CR, Neal SA, Scott RT, Seli E. Diminished ovarian reserve and poor response to stimulation in patients <38 years old: a quantitative but not qualitative reduction in performance. Hum Reprod. 2018;33(8):1489-98. Karlıkaya G, Boynukalin FK, Gultomruk M, Kavrut M, Abalı R, Demir B, et al. Euploidy rates of embryos in young patients with good and low prognosis according to the POSEIDON criteria. Reprod Biomed Online. 2021;42(4):733-41. Su W, Xu J, Arhin SK, Liu C, Zhao J, Lu X. The Feasibility of All-Blastocyst-Culture and Single Blastocyst Transfer Strategy in Elderly Women: A Retrospective Analysis. Biomed Res Int. 2020;2020:5634147. Tannus S, Son W-Y, Dahan MH. Elective single blastocyst transfer in advanced maternal age. J Assist Reprod Genet. 2017;34(6):741-8. Niinimäki M, Suikkari AM, Mäkinen S, Söderström-Anttila V, Martikainen H. Elective single-embryo transfer in women aged 40-44 years. Hum Reprod. 2013;28(2):331-5. Tables Table 1. Baseline clinical characteristics of patients subgrouped by transferred embryo number in the first FET cycle. Group 1 (n=219) Group 2 (n=135) eSET (n=104) DET (n=115) P value eSET (n=83) DET (n=52) P value Age (years) 30.35±2.71 30.98±2.67 0.082 37.82±2.60 37.96±2.41 0.751 BMI (kg/m2) 20.88±3.08 21.45±2.95 0.165 22.44±2.59 21.67±2.38 0.084 Duration of infertility(years) 3.32±1.60 3.41±2.29 0.729 3.84±3.05 4.08±3.37 0.673 Indications for IVF tubal factor 32.69% 45.22% 0.001 45.78% 48.08% 0.743 endometriosis 4.81% 12.17% 1.20% 1.90% male factor 7.69% 13.04% 13.25% 19.23% combined factors 6.73% 7.83% 4.82% 5.77% unknown factors 48.08% 21.74% 34.94% 25.00% AFC 11.20±4.95 12.74±5.21 0.027 10.18±4.78 9.58±4.44 0.464 FSH 7.82±1.90 7.85±2.41 0.932 7.82±2.18 8.45±2.80 0.146 LH 4.63±2.66 5.10±2.87 0.204 4.23±2.03 4.19±1.55 0.911 E2 49.89±58.03 48.76±30.41 0.855 45.38±23.79 53.75±34.65 0.098 P 0.67±0.91 0.83±1.46 0.349 0.71±1.08 0.83±1.55 0.584 PRL 22.78±54.34 19.84±26.58 0.607 22.02±34.89 19.48±27.97 0.658 T 1.03±5.52 0.93±4.61 0.889 1.01±3.82 0.54±0.73 0.374 AMH 3.48±2.07 4.03±2.38 0.069 3.08±2.63 2.87±1.74 0.610 COH protocol GnRH-Agonist 24.04% 31.30% 0.231 32.53% 23.08% 0.238 GnRH-Antagonist 75.96% 68.70% 67.47% 76.92% Total Gn dose (IU) 2549.06±1026.15 2368.73±1028.26 0.196 2934.10±1155.65 3054.72±1178.62 0.559 No. Oocytes retrieved 6.25±2.18 7.03±1.89 0.005 6.34±2.04 6.60±2.21 0.489 EMT on the day of transfer (mm) 11.54±2.26 10.89±2.28 0.037 10.67±2.30 10.93±1.95 0.509 BMI, Body Mass Index; IVF, in vitro fertilization; AFC, antral follicle count; FSH, Follicle-Stimulating Hormone; LH, Luteinizing Hormone; E2, Estradiol; P, Progesterone; PRL, prolactin; T, testosterone; AMH, anti-mullerian hormone, COH, controlled ovarian hyperstimulation; Gn, Gonadotropin Table 2. Pregnancy outcomes of first FET cycle (eSET versus DET) Group 1 Group 2 eSET (N=104) DET (N=115) unadjusted group difference adjusted group difference* eSET (N=83) DET (N=52) unadjusted group difference adjusted group difference* OR (95% CI) P value OR (95% CI) P value OR (95% CI) P value OR (95% CI) P value biochemical pregnancy rate (%) 65 (62.50%) 74 (64.35%) 0.923 (0.532-1.602) 0.777 0.663 (0.354-1.241) 0.199 30 (36.14%) 29 (55.77%) 0.449 (0.221-0.910) 0.026 0.409 (0.189-0.888) 0.024 clinical pregnancy rate (%) 59 (56.73%) 71 (61.74%) 0.813 (0.473-1.395) 0.451 0.585 (0.315-1.089) 0.091 28 (33.73%) 24 (50.00%) 0.509 (0.251-1.034) 0.062 0.473 (0.219-1.019) 0.056 ongoing pregnancy rate (%) 50 (48.08%) 64 (55.65%) 0.738 (0.433-1.256) 0.263 0.614 (0.335-1.123) 0.113 17 (20.48%) 20 (38.46%) 0.412 (0.190-0.892) 0.024 0.358 (0.155-0.828) 0.016 live birth rate (%) 48 (46.15%) 60 (52.17%) 0.786 (0.462-1.337) 0.374 0.622 (0.340-1.140) 0.124 17 (20.48%) 20 (38.46%) 0.412 (0.190-0.892) 0.024 0.358 (0.155-0.828) 0.016 multiple birth rate (%) 0 12/60 (20.00%) / 0.001 / / 0 4/20 (20.00%) / 0.155 / / * Adjusted for age, BMI, indications for IVF, AFC, EMT, No. oocytes retrieved. Table 3. Logistic regression analysis on the live birth rate in patients with unexpected poor prognosis . Group 1 Group 2 univariate analysis multivariate analysis univariate analysis multivariate analysis OR (95% CI) P value OR (95% CI) P value OR (95% CI) p value OR (95% CI) P value age 0.959 (0.869-1.059) 0.409 0.959 (0.869-1.059) 0.409 0.759 (0.624-0.922) 0.006 0.751 (0.605-0.932) 0.009 Body Mass Index / BMI 0.969 (0.887-1.059) 0.490 0.969 (0.887-1.059) 0.490 0.900 (0.769-1.053) 0.188 0.939 (0.793-1.113) 0.471 AFC 0.986 (0.936-1.039) 0.598 0.986 (0.936-1.039) 0.598 1.042 (0.963-1.128) 0.302 1.017 (0.932-1.110) 0.699 endometrial thickness 1.004 (0.894-1.127) 0.948 1.004 (0.894-1.127) 0.948 1.082 (0.907-1.291) 0.381 1.020 (0.836-1.246) 0.842 No. oocytes retrieved 1.076 (0.945-1.226) 0.266 1.076 (0.945-1.226) 0.266 1.007 (0.841-1.207) 0.939 0.979 (0.807-1.187) 0.827 No. transferred embryos 0.786 (0.462-1.337) 0.374 0.786 (0.462-1.337) 0.374 0.412 (0.190-0.892) 0.024 0.367 (0.161-0.840) 0.018 Additional Declarations No competing interests reported. Supplementary Files SupplementaryTable1.docx Supplementary Table 1. Baseline clinical characteristics of patients with unexpected poor prognosis. Cite Share Download PDF Status: Posted Version 1 posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. 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-2752135","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":187679508,"identity":"4d1fd0a6-fefb-45d9-801a-3bba325105e9","order_by":0,"name":"Rang Liu","email":"","orcid":"","institution":"Center for Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Rang","middleName":"","lastName":"Liu","suffix":""},{"id":187679509,"identity":"97c3853b-866f-4b35-8741-9610b80c6dda","order_by":1,"name":"Qiuju 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518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Huiqing","middleName":"","lastName":"He","suffix":""},{"id":187679512,"identity":"ac4cb5ee-2814-4bc2-935b-23438ffb5721","order_by":4,"name":"Chang Xu","email":"","orcid":"","institution":"Intelligence Hospital Research Academy, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Chang","middleName":"","lastName":"Xu","suffix":""},{"id":187679513,"identity":"75632cb1-ecbe-430f-8bb2-1ad82f4bfd41","order_by":5,"name":"Jiali Feng","email":"","orcid":"","institution":"Center for Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Jiali","middleName":"","lastName":"Feng","suffix":""},{"id":187679514,"identity":"5aab5a92-678d-4d72-929b-2c5c21939a3c","order_by":6,"name":"Miaoling Song","email":"","orcid":"","institution":"Center for Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Miaoling","middleName":"","lastName":"Song","suffix":""},{"id":187679515,"identity":"8f56c8d4-b157-4d0b-aed2-e49bbc2ffab1","order_by":7,"name":"Yanpei Cao","email":"","orcid":"","institution":"Center for Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Yanpei","middleName":"","lastName":"Cao","suffix":""},{"id":187679517,"identity":"a286fe5f-0637-4ac1-bab3-27143f89f0b0","order_by":8,"name":"Tianren Wang","email":"","orcid":"","institution":"Center for Reproductive Medicine, The University of Hong Kong-Shenzhen Hospital, Shenzhen, Guangdong 518000","correspondingAuthor":false,"submittingAuthor":false,"prefix":"","firstName":"Tianren","middleName":"","lastName":"Wang","suffix":""},{"id":187679519,"identity":"24619b65-4148-4516-9e0e-31fe76405ac0","order_by":9,"name":"Xi Xia","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA5ElEQVRIie3PuwrCMBSA4ciBdAl2TbH4DEcCXhZ9FcU1iKMiWKFrwVXwJZw6N3RwqbjWzcuqoJuDg41zaXVzyD8lkI+TQ4jJ9I8BIRFBXret4HNn1e/IuC2cINEnwuh3o+6TwWYlP4SUEtyyRvREXtk4N3V5yK5LCZzOaQFxfNpXAXJo1UZDVOEw+xgVQhYQGyCKGHLaWcsmVyFkhNFaEaFQWagXcoaHRBOvnOgpcTaFY8o0icuJ3iV2kaMTSIG7cMsolOyC+0Q8rq+5t7SSxnEaznq25Z8uRSQn+O25yWQymXJ6AzTWQvEoIIERAAAAAElFTkSuQmCC","orcid":"","institution":"Center for Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, Guangdong 518036","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"Xi","middleName":"","lastName":"Xia","suffix":""}],"badges":[],"createdAt":"2023-03-29 13:29:28","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-2752135/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-2752135/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":35109445,"identity":"87f49151-3186-4d53-a033-b31551a8c7f9","added_by":"auto","created_at":"2023-03-31 15:18:02","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":65367,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe flowchart of the study design.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-2752135/v1/d3cecf6717db6b1dd45f3e60.png"},{"id":35109446,"identity":"86f9d442-4a1a-457e-a61a-9f4e742d9adf","added_by":"auto","created_at":"2023-03-31 15:18:03","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":67151,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eThe primary outcomes of Poseidon Group 1 and 2 with different transferred embryo numbers. \u003c/strong\u003eeSET = elective single embryo transfer; DET = double embryo transfer.\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-2752135/v1/0cbeeeb3281ff49a87470dd8.png"},{"id":35110416,"identity":"cab1a465-0842-4f7f-a943-2324a7e43556","added_by":"auto","created_at":"2023-03-31 15:26:03","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":838390,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-2752135/v1/d488c568-fb90-4e39-9611-796780a9b052.pdf"},{"id":35109447,"identity":"a58644df-c2df-4a53-8cb1-2994a727437e","added_by":"auto","created_at":"2023-03-31 15:18:03","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":22459,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eSupplementary Table 1. Baseline clinical characteristics of patients with unexpected poor prognosis.\u003c/strong\u003e\u003c/p\u003e","description":"","filename":"SupplementaryTable1.docx","url":"https://assets-eu.researchsquare.com/files/rs-2752135/v1/5b207413650d7fa4f19699f8.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"What is the Optimal Number of Embryos to Transfer for Poseidon Group 1 and Group 2? A retrospective study","fulltext":[{"header":"Introduction","content":"\u003cp\u003eDespite the spectacular development and fruitful achievement, assisted reproductive technology (ART) has not yet perfectly satisfied every patient. Patients with diminished ovarian reserve (DOR) or poor ovarian response (POR) are considered one of the most difficult populations for their frustrating outcomes even after ART treatment, making their management a thorny issue for reproductive clinicians [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. To address the heterogeneity in the definition, in 2011 the European Society of Human Reproduction and Embryology (ESHRE) standardized poor responders by the Bologna criteria [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. It was pointed out that the Bologna criteria might not be practical or efficient enough to manage patients since heterogeneity of treatment strategy remained after categorization. The 2016 Patient-Oriented Strategy Encompassing IndividualizeD Oocyte Number (POSEIDON) group more detailly stratified the poor responders into 4 groups by age, ovarian biomarkers, and the number of oocytes retrieved, transiting the definition of POR to the concept of low prognosis. Under the new criteria, patients are further classified as unexpected low-prognosis if they presented a favorable ovarian reserve test (antral follicle count (AFC)\u0026thinsp;\u0026ge;\u0026thinsp;5 or/and anti-mullerian hormone (AMH)\u0026thinsp;\u0026ge;\u0026thinsp;1.2 ng/ml) but with a low response in a standard ovarian stimulation cycle (\u0026le;\u0026thinsp;9 oocytes), and as expected low-prognosis if low ovarian reserve were shown [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eAlthough Poseidon stratification ameliorates the difficulties in counseling and prognosis prediction, it continued to challenge experts that how to manage these low-prognosis patients in each node of ART treatment to optimize the outcomes. Scholars have intensely discussed the pretreatment, adjuvant treatment, ovarian stimulation protocols, and maximization of oocyte or embryo usability by laboratory techniques [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Up to the present, research has yet to pay much attention to the embryo transfer strategy for low-prognosis patients under the Poseidon classification, which is a question eventually inevitable to be answered.\u003c/p\u003e \u003cp\u003eAs assisted conception technologies progressed, high-quality success was more and more pursued rather than just obtaining live births. Ideally, successful in vitro fertilization (IVF) treatment was expected to result in one healthy singleton by an optimal embryo transfer strategy. However, in order to improve the prognosis of unfavorable patients, the transfer of more than one embryo would be considered, which was also out of the wishes for reducing unnecessary multiple transfers and relieving the patient\u0026rsquo;s anxiety. Unfortunately, patients were exposed to the potential risk of multiple births. While maintaining a satisfactory delivery rate, multiple births should be controlled by various strategies to reduce complications, including adverse maternal and neonatal outcomes [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Early in the end of 20th century, elective single embryo transfer (eSET) was recommended to mitigate the risk of multiple births [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e]. The 2013 American Society for Reproductive Medicine and Society for Assisted Reproductive Technology (ASRM/SART) committee opinion suggested young patients with favorable prognoses be transferred 1\u0026ndash;2 cleavage-stage embryos or single blastocyst [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Further defining the concept of \u0026ldquo;favorable\u0026rdquo; in detail, the 2021 ASRM/SART committee opinion recommended single embryo transfer for patients\u0026thinsp;\u0026le;\u0026thinsp;37 years with favorable prognoses, and that increased embryo number by age or if the embryo was not euploid or favorable [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Since 42%-45% of favorable prognosis patients in the US did not undergo eSET, leading to an unacceptable multiple birth rate, it was recently proposed to enhance adherence to the guideline [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eParadoxical as it may seem, patients classified as low prognosis by Poseidon criteria undergoing blastocyst transfer in their first frozen embryo transfer cycle (FET) were associated with a favorable prognosis according to the 2021 ASRM/SART committee opinion [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The appropriate number of embryos to transfer for this patient population remains to be addressed. Thus, the aim of this article was to investigate the optimized number of transferred embryos to improve the prognosis of unexpected low-prognosis patients by comparing the clinical outcomes of different blastocyst transfer protocols in the first FET among Poseidon Groups 1 and 2.\u003c/p\u003e"},{"header":"Materials And Methods","content":"\u003cp\u003e\u003cstrong\u003ePatient Selection\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis was a retrospective study conducted among patients who underwent ART treatment at the Peking University Shenzhen Hospital Reproductive Medicine Center between January 2018 and December 2021. 2970 patients fulfilling the POSEIDON criteria who underwent FET cycles were sorted out and classified accordingly\u0026nbsp;[3]. Group 1: Patients \u0026lt;35 years with AFC \u0026ge;5 and/or AMH \u0026ge;1.2 ng/mL and with an unexpected poor or suboptimal ovarian response (retrieved \u0026le;9 oocytes). Group 2: Patients \u0026ge;35 years with AFC \u0026ge;5 and/or AMH \u0026ge;1.2 ng/mL and with an unexpected poor or suboptimal ovarian response. As reported in a previous study, AMH and AFC had equivalent accuracy and efficacy for patient stratification\u0026nbsp;[10]. In our study, AMH rather than AFC was used for grouping since it was more objective\u0026nbsp;with less potential bias. Oocyte retrieval in Group 1 or Group 2 was conducted under standard ovarian stimulation. Patients classified to Poseidon Group 3 and Group 4, who underwent preimplantation genetic screening/diagnosis (PGS/PGD), who were with previous fresh embryo transfers or FET history were excluded. Patients\u0026nbsp;with only one cryopreserved embryo at the time of transfer\u0026nbsp;were also eliminated. Only patients from Group 1 and Group 2 with blastocysts transferred in their first FET cycle and had completed the follow-up were included for analysis.\u0026nbsp;Outcome follow-ups were conducted offline when patients returned to the center or online by telephone. Based on the number of blastocysts to transfer, patients were further divided into subgroups including elective single embryo transfer (e-SET) and double embryo transfer (DET) (Figure I).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOvarian Stimulation\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eStandard ovarian stimulation protocols including gonadotrophin-releasing hormone (GnRH) antagonist and GnRH agonist (ultra-long/long) were used individually\u0026nbsp;[11-13]. Based on ovarian reserve, age,\u0026nbsp;body mass index (BMI),\u0026nbsp;and previous stimulation outcome if available, patients received subcutaneous injections of recombinant gonadotropin (recombinant FSH (GONAL-f, Merck Serono, Germany) /purified hMG (Urofollitropin, Livzon Pharmaceuticals, China) /recombinant FSH plus hMG or recombinant LH (Luveris, Merck Serono, Germany), 2:1 ratio) with an initial daily dosage of 150-450IU. GnRH-antagonist (Cetrotide, Merck Serono,\u0026nbsp;Germany or Ganirelix, MSD, USA) was administered starting from the day when the dominant follicle reached 12-14 mm in diameter until the trigger day. GnRH-agonist (Decapeptyl,\u0026nbsp;Ferring pharmaceuticals, Switzerland) was initiated prior to ovarian stimulation with one to three injections to achieve downregulation in the ultra-long protocol or from the previous mid-luteal phase in the long protocol. Recombinant HCG\u0026nbsp;(Choriogonadotropin alfa, Merck Serono, Germany) or recombinant HCG combined with GnRH agonist was applied to trigger the final maturation when at least two lead follicles reached greater than 18 mm in diameter. Oocyte retrieval was conducted 36-38 hours after triggering.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eOutcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe primary outcomes were the live birth rate, defined as the rate of patients\u0026nbsp;giving birth\u0026nbsp;to a fetus of any living sign after 28 weeks of gestation, and the multiple birth rate, defined as the rate of giving birth to more than one living infant among all live births. The secondary outcomes included (i) biochemical pregnancy rate defined as the rate of patients with positive detection of urine or serum beta-HCG test, (ii) clinical pregnancy rate, defined as the rate of patients with pregnancy diagnosed by ultrasonographic confirmation of intrauterine gestational sac 28 days after embryo transfer, (iii) ongoing pregnancy rate, defined as the rate of patient with ultrasonographic confirmation of intrauterine fetal heart activity beyond 12 weeks of gestation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eStatistics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll the statistical analysis was performed by SPSS statistics version 26.0 (IBM, Armonk, NY, USA). Continuous data were expressed as mean \u0026plusmn; SD and compared by Student\u0026rsquo;s t-test. Categorical data were presented as frequencies and percentages. The Chi-square test or Fisher\u0026rsquo;s exact test was used to compare rates in the baseline characteristics. Logistic regression analysis was applied to output\u0026nbsp;the unadjusted odds ratio (OR) and the adjusted OR (aOR) with 95% CI for the rates of outcomes. Potential confounding variables were adjusted including age, BMI, indications for IVF, AFC, endometrium thickness (EMT) on the day of transfer, and the number of oocytes retrieved. Finally, univariate and multivariate analyses were performed to analyze the associated variables for live birth rates and the results were reported as OR with 95% CI. A two-sided \u003cem\u003eP\u003c/em\u003e value \u0026lt;0.05 was considered statistically significant.\u003c/p\u003e"},{"header":"Results","content":"\u003cp\u003e\u003cstrong\u003eBaseline Clinical Characteristics\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eIn this study, a total of 354 frozen blastocyst transfer cycles from Poseidon Group 1 (N = 219) and Group 2 (N = 135) were analyzed. Supplementary Table 1 summarized general patient characteristics. Compared to Poseidon Group 1, Group 2 had significantly higher age (37.87\u0026plusmn;2.52 versus 30.68\u0026plusmn;2.70, \u003cem\u003eP\u003c/em\u003e = 0.000), lower AFC (9.95\u0026plusmn;4.65 versus 12.01\u0026plusmn;5.13, \u003cem\u003eP\u003c/em\u003e = 0.000), lower AMH (3.00\u0026plusmn;2.32 versus 3.77\u0026plusmn;2.25, \u003cem\u003eP\u003c/em\u003e = 0.002) and higher total gonadotropin (Gn) dose (2980.56\u0026plusmn;1161.65 versus 2454.37\u0026plusmn;1028.87, \u003cem\u003eP\u003c/em\u003e = 0.000). Basal hormonal level (except LH), controlled ovarian hyperstimulation (COH) protocol, and the number of oocytes retrieved were comparable between Group 1 and Group 2. Indications for IVF (\u003cem\u003eP\u003c/em\u003e = 0.028) and BMI (22.14\u0026plusmn;2.53 versus 21.18\u0026plusmn;3.02, \u003cem\u003eP\u003c/em\u003e = 0.002) were significantly different between groups.\u003c/p\u003e\n\u003cp\u003eThe number of patients/cycles transferring one embryo and transferring two embryos was 104 versus 115 in Poseidon Group 1 and 83 versus 52 in Group 2, respectively. The baseline characteristics of subgroups were summarized in Table 1. Significant differences existed in comparison of indications for IVF (\u003cem\u003eP\u003c/em\u003e = 0.001), AFC (11.20\u0026plusmn;4.95 versus 12.74\u0026plusmn;5.21, \u003cem\u003eP\u003c/em\u003e = 0.027), and number of oocytes retrieved (6.25\u0026plusmn;2.18 versus 7.03\u0026plusmn;1.89, \u003cem\u003eP\u003c/em\u003e = 0.005), EMT on the day of transfer (11.54\u0026plusmn;2.26 versus 10.89\u0026plusmn;2.28, \u003cem\u003eP\u003c/em\u003e = 0.037) between eSET and DET in Group 1. All indicators were comparable between eSET and DET within Group 2.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Outcomes\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFor Poseidon Group 1, the live birth rate per embryo transfer was 46.15% in the eSET group and 52.17% in the DET group (OR 0.786, 95% CI 0.462-1.337, \u003cem\u003eP\u003c/em\u003e = 0.374; aOR 0.622, 95% CI 0.340-1.140, \u003cem\u003eP\u003c/em\u003e = 0.124). However, a multiple birth rate of 20.00% was shown in the DET group (\u003cem\u003eP\u003c/em\u003e = 0.001) (Table 2, Figure 2). Similarly, biochemical pregnancy rate, clinical pregnancy rate and ongoing pregnancy rate increased from 62.50% to 64.35% (OR 0. 923, 95% CI 0.532-1.602, \u003cem\u003eP\u003c/em\u003e = 0.777; aOR 0.663, 95% CI 0.354-1.241, \u003cem\u003eP\u003c/em\u003e = 0.199), 56.73% to 61.74% (OR 0.813, 95% CI 0.473-1.395, \u003cem\u003eP\u003c/em\u003e = 0.451; aOR 0.585, 95% CI 0.315-1.089, \u003cem\u003eP\u003c/em\u003e = 0.091), and 48.08% to 55.65% (OR 0.738, 95% CI 0.433-1.256, \u003cem\u003eP\u003c/em\u003e = 0.263; aOR 0.614, 95% CI 0.335-1.123, \u003cem\u003eP\u003c/em\u003e = 0.113) without statistically significant differences when comparing the eSET group to the DET group (Table 2). \u003c/p\u003e\n\u003cp\u003eThe live birth rate in the eSET group was significantly different from that in the DET group (20.48% versus 38.46%, OR 0.412, 95% CI 0.190-0.892, \u003cem\u003eP\u003c/em\u003e = 0.024; aOR 0.358, 95% CI 0.155-0.828, \u003cem\u003eP\u003c/em\u003e = 0.016) in Poseidon Group 2. The multiple birth rate increased to 20.00% in the DET group without significance compared to the eSET group (\u003cem\u003eP\u003c/em\u003e = 0.155) (Table 2, Figure 2). The value for the ongoing pregnancy rate was in accord with the live birth rate. Biochemical and clinical pregnancy rates increased from 36.14% to 55.77% (OR 0.499, 95% CI 0.221-0.910, \u003cem\u003eP\u003c/em\u003e = 0.026; aOR 0.409, 95% CI 0.189-0.888, \u003cem\u003eP\u003c/em\u003e = 0.024) and 33.73% to 50.00% (OR 0.509, 95% CI 0.251-1.034, \u003cem\u003eP\u003c/em\u003e = 0.062; aOR 0.473, 95% CI 0.219-1.019, \u003cem\u003eP\u003c/em\u003e = 0.056) comparing the eSET group to the DET group (Table 2). \u003c/p\u003e\n\u003cp\u003eAmong the potential associated variables on the live birth rate, including age, BMI, AFC, EMT, the number of oocytes retrieved, and the number of transferred embryos, univariate and multivariate analyses showed that in Poseidon Group 1, none of the above variables was found to be significantly associated with the live birth rate. However, for Group 2, age (OR 0.759, 95% CI 0.624-0.922, \u003cem\u003eP\u003c/em\u003e = 0.006 and OR 0.751, 95% CI 0.605-0.932, \u003cem\u003eP\u003c/em\u003e = 0.009) and the number of transferred (OR 0.412, 95% CI 0.190-0.892, \u003cem\u003eP\u003c/em\u003e = 0.024 and OR 0.367, 95% CI 0.161-0.840, \u003cem\u003eP\u003c/em\u003e = 0.018) embryos were shown to have a significant association with the live birth rate (Table 3).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eTo the best of our knowledge, there was a lack of the discussion about the management of Poseidon low-prognosis patients specific to the embryo transfer protocols, including the decisions on embryo quantity and quality. Our study showed the novelty that the embryo number to transfer for the Poseidon Group was focused on for the first time. The current study analyzed the first FET with blastocyst transfer, and it was observed in Poseidon Group 1 that compared to single blastocyst transfer, an upward trend was present among the clinical outcomes of double blastocyst transfer but without significance, which was accompanied by a significant increase of multiple birth rate. In Poseidon Group 2, double blastocyst transfer was significantly associated with the improvement in clinical outcomes with multiple birth rate not significantly increased. Furthermore, age and the number of transferred embryos were demonstrated to be crucial variables for the live birth rate in unexpected low-prognosis patients\u0026thinsp;\u0026ge;\u0026thinsp;35 years.\u003c/p\u003e \u003cp\u003eEmbryo transfer strategy, as the most crucial part of controlling multiple births, has been constantly discussed in different patient populations. Focusing on poor responders, an early study found double embryo transfer might lead to a higher live birth rate than those with single embryo transfer, with a modest increase in the multiple birth rate (9.1%) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e]. In 2015, Gleicher et al retrospectively analyzed the live birth rates of transferring embryos in various numbers among poor responders by Bologna criteria. With age stratification, the results showed that young patients had a satisfactory live birth rate of 33% whether with non-elective one or two embryos transferred. Live birth rates in patients aged 35\u0026ndash;37 and 38\u0026ndash;40 seemed to associate with embryo number. For patients with advanced age, the rates were as low as 5.9%-7.4% even after three embryos were transferred [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePatient prognosis was considered one of the critical factors for the decisions on transfer protocols. Various studies investigated embryo transfer strategies for patients with different prognoses. However, the standard of prognosis was not consistently defined in these studies. Loendersloot et al. defined women\u0026thinsp;\u0026le;\u0026thinsp;35 years who underwent their first IVF/ICSI cycle as good prognosis and women\u0026thinsp;\u0026ge;\u0026thinsp;39 years as poor prognosis. Women aged between 35\u0026ndash;39 years, young patients undergoing their first IVF without a top-quality embryo, or having at least one failed IVF cycle were classified as intermediate prognosis [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Another study classified patients\u0026rsquo; prognoses according to their previous IVF history and outcomes, as well as whether they had extra embryos for cryopreservation [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Gleicher et al. defined poor responders under Bologna criteria as a very poor prognosis population [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e]. Since 2016, Poseidon criteria have converted the conception of poor responder into low prognosis. Our study provided a novel comparative analysis under the Poseidon low prognosis conception and the favorable clinical setting according to the 2021 ASRM/SART guideline.\u003c/p\u003e \u003cp\u003eIn our study, Poseidon Group 1 did not obviously benefit from double blastocysts transfer, which was associated with a slight increase of 6.02% in the live birth rate. However, the benefits were largely offset by the multiple birth rates significantly rising to 20.00% (Table\u0026nbsp;2, Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). It was worth mentioning that the live birth rate could reach 46.15% with elective single blastocyst transfer. Similar to the study by Gleicher et al [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e], although defined as low prognosis by Poseidon criteria, patients aged\u0026thinsp;\u0026le;\u0026thinsp;35 years seemed to have quite satisfying outcomes. A previous study reported that the blastulation rate of embryos and the live birth rates per embryo transfer cycle in young patients with low ovarian response were equivalent to those with a normal response, indicating that oocyte quality may not decline in this population [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e]. It was demonstrated in a more recent study that euploidy rates in Poseidon Group 1 were not significantly different from good-prognosis patients and were not influenced by the ovarian response [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e]. This information may give a hint about the embryo accumulation protocol. Moreover, Poseidon Group 1, as the young unexpected low-prognosis patients, possibly could be regarded as good prognosis once they underwent blastocyst transfer in the first FET. Given that acceptable outcomes were observed in eSET and multiple birth rates raised in DET, this patient population should be encouraged to adopt single embryo transfer, as the 2021 ASRM/SART embryo transfer guideline recommended [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eOur study demonstrated a significant association between embryo number and clinical outcomes in Poseidon Group 2. Double blastocyst transfer showed its superiority in promoting the live birth rate from 20.48\u0026ndash;38.46%. Logistic regression analysis suggested both age and embryo number as important variables in this group. Heterogeneity remained in the efficiency of different embryo transfer strategies for aged patients in the previous clinical research. A retrospective analysis including 155 patients with ages\u0026thinsp;\u0026ge;\u0026thinsp;35 years reported that the live birth rate of double blastocyst transfer did not differ from single blastocyst transfer (46.5% versus 37.0%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.228), whereas the risks of preterm birth and low birth weight increased [\u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e]. Another retrospective cohort for patients\u0026thinsp;\u0026ge;\u0026thinsp;40 years demonstrated that compared to elective single blastocyst transfer, double blastocyst transfer showed a similar live birth rate (22.8% versus 20%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.20). However, elective double blastocyst transfer, which meant extra blastocyst available for cryopreservation, achieved significant improvement in the live birth rate (30.6% versus 20%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.017) [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e]. The study targeting patients aged 40\u0026ndash;44 years by Niinim\u0026auml;ki, M et al. showed the opposite result that advanced patients had higher cumulative live birth rates with elective single embryo transfer than with double embryo transfer (22.7% versus 13.2%, \u003cem\u003eP\u003c/em\u003e\u0026thinsp;=\u0026thinsp;0.002) [\u003cspan citationid=\"CR22\" class=\"CitationRef\"\u003e22\u003c/span\u003e]. These studies did not further stratify the patients according to their prognosis, which was an important consideration for making a transfer strategy. For Poseidon Group 2, it seemed that double embryo transfer would be preferred when merely discussing the live birth rate. Meanwhile, the potential accompanying risk of multiple births should be noticed.\u003c/p\u003e \u003cp\u003eWith the restriction of local policies, cases of transferring more than two blastocysts were lacking. It is expected that data about clinical outcomes with multiple embryo transfers for Poseidon patients could be discussed worldwide in the future. We also observed that many studies about embryo transfer refined the patients\u0026rsquo; age when discussing the aged population, and Logistic regression demonstrated the significance of age for the live birth rate. It may inspire us to further stratify the patients\u0026rsquo; age in the following study to test the results in each refining age group. Our study was also limited in the nature of the retrospective design with inherent bias and unknown confounders. Another limitation was that only Poseidon Group 1 and Group 2 were included in the present study given that clinical data of Poseidon Group 3 and Group 4 were relatively fewer for analysis and collecting work was still ongoing. A large-scale multi-center prospective analysis is expected to further investigate the embryo transfer strategy for Poseidon patients.\u003c/p\u003e \u003cp\u003e In conclusion, following the embryo transfer guideline, we advocated single blastocyst transfer as the first option in the first FET cycle for Poseidon Group 1. Poseidon Group 2 could benefit from double embryo transfer. When multiple embryo transfer was selected, the risk of multiple birth rates should be considered and personal willingness, basic health conditions as well as economic factors should be fully evaluated. A more scientific discussion about the embryo transfer strategy under Poseidon criteria might base on a reasonable age stratification. More precise management based on Poseidon criteria may be the treatment strategy for poor responders in the future.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cp\u003eeSET=elective single embryo transfer; DET=double embryo transfer; ART=assisted reproductive technology; DOR=diminished ovarian reserve; POR=poor ovarian response; AFC=antral follicle count; AMH=\u0026nbsp;anti-mullerian hormone\u003cstrong\u003e;\u003c/strong\u003e IVF=in vitro fertilization; FET= frozen embryo transfer; PGS/PGD=preimplantation genetic screening/diagnosis; ICM=inner cell mass; TE=trophectoderm; BMI=body mass index; EMT=endometrium thickness; Gn=gonadotropin; COH=controlled ovarian hyperstimulation\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eEthics approval was obtained from the committee of\u0026nbsp;Peking University Shenzhen Hospital without the need for informed consent.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData Availability Statements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe data underlying this article will be shared on reasonable request to the corresponding author.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare no competing interests.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis work was supported by the Shenzhen Fundamental Research Program (JCYJ20200109150429414).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026rsquo; contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eR.L. \u0026ndash; Manuscript Drafting and Data Analysis; Q.Z. \u0026ndash; Review and Editing; R.L., Q.Z. and X.X. \u0026ndash; Study Design; L.G., H.H. \u0026ndash; Data Verification; J.F., M.S. and Y.C. \u0026ndash; Data Collection; C.X. \u0026ndash; Statistical Tutoring; T.W. and X.X. \u0026nbsp;\u0026ndash; Conceptualization, Critical Discussion and Supervision. All authors reviewed the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgments\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe thank all the staff in the center for reproductive medicine of Peking University Shenzhen hospital and all the patients who underwent ART treatment at our center.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eCedars MI. Managing poor ovarian response in the patient with diminished ovarian reserve. Fertil Steril. 2022;117(4):655-6.\u003c/li\u003e\n\u003cli\u003eFerraretti AP, La Marca A, Fauser BCJM, Tarlatzis B, Nargund G, Gianaroli L. ESHRE consensus on the definition of \u0026apos;poor response\u0026apos; to ovarian stimulation for in vitro fertilization: the Bologna criteria. Hum Reprod. 2011;26(7):1616-24.\u003c/li\u003e\n\u003cli\u003eAlviggi C, Andersen CY, Buehler K, Conforti A, De Placido G, Esteves SC, et al. A new more detailed stratification of low responders to ovarian stimulation: from a poor ovarian response to a low prognosis concept. Fertil Steril. 2016;105(6):1452-3.\u003c/li\u003e\n\u003cli\u003eBergh C, Kamath MS, Wang R, Lensen S. Strategies to reduce multiple pregnancies during medically assisted reproduction. Fertil Steril. 2020;114(4):673-9.\u003c/li\u003e\n\u003cli\u003eVilska S, Tiitinen A, Hyd\u0026eacute;n-Granskog C, Hovatta O. Elective transfer of one embryo results in an acceptable pregnancy rate and eliminates the risk of multiple birth. Hum Reprod. 1999;14(9):2392-5.\u003c/li\u003e\n\u003cli\u003eCriteria for number of embryos to transfer: a committee opinion. Fertil Steril. 2013;99(1):44-6.\u003c/li\u003e\n\u003cli\u003eGuidance on the limits to the number of embryos to transfer: a committee opinion. Fertil Steril. 2021;116(3):651-4.\u003c/li\u003e\n\u003cli\u003eD\u0026apos;Hooghe T. Multiple live birth rate more than 60% after assisted reproductive technology treatment in patients with favorable prognosis: opportunity to address a reproductive public health and economic burden by improved adherence to guidelines combined with increased patient access to assisted reproductive technology care. Fertil Steril. 2022;117(3):560-1.\u003c/li\u003e\n\u003cli\u003eGingold JA, Fazzari M, Gerber R, Kappy M, Goodman M, Lieman H, et al. Adherence to embryo transfer guidelines in favorable-prognosis patients aged less than 35 years using autologous oocytes and in recipients using donor oocytes: a Society for Assisted Reproductive Technology Clinic Outcome Reporting System study. Fertil Steril. 2022;117(3):548-59.\u003c/li\u003e\n\u003cli\u003eEsteves SC, Yarali H, Vuong LN, Carvalho JF, \u0026Ouml;zbek İY, Polat M, et al. Antral follicle count and anti-M\u0026uuml;llerian hormone to classify low-prognosis women under the POSEIDON criteria: a classification agreement study of over 9000 patients. Hum Reprod. 2021;36(6):1530-41.\u003c/li\u003e\n\u003cli\u003eChinta P, Antonisamy B, Mangalaraj AM, Kunjummen AT, Kamath MS. POSEIDON classification and the proposed treatment options for groups 1 and 2: time to revisit? A retrospective analysis of 1425 ART cycles. Hum Reprod Open. 2021;2021(1):hoaa070.\u003c/li\u003e\n\u003cli\u003eYang R, Zhang C, Chen L, Wang Y, Li R, Liu P, et al. Cumulative live birth rate of low prognosis patients with POSEIDON stratification: a single-centre data analysis. Reprod Biomed Online. 2020;41(5):834-44.\u003c/li\u003e\n\u003cli\u003eLiu X, Xu J, Bi L, Liu P, Jiao X. Growth Hormone Cotreatment for Low-Prognosis Patients According to the POSEIDON Criteria. Front Endocrinol (Lausanne). 2021;12:790160.\u003c/li\u003e\n\u003cli\u003eJonsdottir I, Lundin K, Bergh C. Double embryo transfer gives good pregnancy and live birth rates in poor responders with a modest increase in multiple birth rates: results from an observational study. Acta Obstet Gynecol Scand. 2011;90(7):761-6.\u003c/li\u003e\n\u003cli\u003eGleicher N, Vega MV, Darmon SK, Weghofer A, Wu Y-G, Wang Q, et al. Live-birth rates in very poor prognosis patients, who are defined as poor responders under the Bologna criteria, with nonelective single embryo, two-embryo, and three or more embryos transferred. Fertil Steril. 2015;104(6):1435-41.\u003c/li\u003e\n\u003cli\u003evan Loendersloot L, van Wely M, Goddijn M, Repping S, Bossuyt P, van der Veen F. Pregnancy and twinning rates using a tailored embryo transfer policy. Reprod Biomed Online. 2013;26(5):462-9.\u003c/li\u003e\n\u003cli\u003eKissin DM, Kulkarni AD, Kushnir VA, Jamieson DJ. Number of embryos transferred after in vitro fertilization and good perinatal outcome. Obstet Gynecol. 2014;123(2 Pt 1):239-47.\u003c/li\u003e\n\u003cli\u003eMorin SJ, Patounakis G, Juneau CR, Neal SA, Scott RT, Seli E. Diminished ovarian reserve and poor response to stimulation in patients \u0026lt;38 years old: a quantitative but not qualitative reduction in performance. Hum Reprod. 2018;33(8):1489-98.\u003c/li\u003e\n\u003cli\u003eKarlıkaya G, Boynukalin FK, Gultomruk M, Kavrut M, Abalı R, Demir B, et al. Euploidy rates of embryos in young patients with good and low prognosis according to the POSEIDON criteria. Reprod Biomed Online. 2021;42(4):733-41.\u003c/li\u003e\n\u003cli\u003eSu W, Xu J, Arhin SK, Liu C, Zhao J, Lu X. The Feasibility of All-Blastocyst-Culture and Single Blastocyst Transfer Strategy in Elderly Women: A Retrospective Analysis. Biomed Res Int. 2020;2020:5634147.\u003c/li\u003e\n\u003cli\u003eTannus S, Son W-Y, Dahan MH. Elective single blastocyst transfer in advanced maternal age. J Assist Reprod Genet. 2017;34(6):741-8.\u003c/li\u003e\n\u003cli\u003eNiinim\u0026auml;ki M, Suikkari AM, M\u0026auml;kinen S, S\u0026ouml;derstr\u0026ouml;m-Anttila V, Martikainen H. Elective single-embryo transfer in women aged 40-44 years. Hum Reprod. 2013;28(2):331-5.\u003c/li\u003e\n\u003c/ol\u003e"},{"header":"Tables","content":"\u003ctable align=\"\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"7\" width=\"100%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 1. Baseline clinical characteristics of patients subgrouped by transferred embryo number in the first FET cycle.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" width=\"37.22854188210962%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1 (n=219)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" width=\"35.16028955532575%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2 (n=135)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u003cstrong\u003eeSET (n=104)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDET (n=115)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u003cstrong\u003eeSET (n=83)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDET (n=52)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e30.35\u0026plusmn;2.71\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e30.98\u0026plusmn;2.67\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.082\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e37.82\u0026plusmn;2.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e37.96\u0026plusmn;2.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.751\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eBMI (kg/m2)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e20.88\u0026plusmn;3.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e21.45\u0026plusmn;2.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.165\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e22.44\u0026plusmn;2.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e21.67\u0026plusmn;2.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.084\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDuration of infertility(years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e3.32\u0026plusmn;1.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e3.41\u0026plusmn;2.29\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.729\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e3.84\u0026plusmn;3.05\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e4.08\u0026plusmn;3.37\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.673\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eIndications for IVF\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;tubal factor\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e32.69%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e45.22%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e45.78%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e48.08%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"5\" width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.743\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.05282112845138%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;endometriosis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e4.81%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e12.17%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e1.20%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e1.90%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.05282112845138%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;male factor\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e7.69%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e13.04%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e13.25%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e19.23%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.05282112845138%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;combined factors\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e6.73%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e7.83%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e4.82%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e5.77%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.05282112845138%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;unknown factors\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e48.08%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e21.74%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e34.94%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e25.00%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAFC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e11.20\u0026plusmn;4.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e12.74\u0026plusmn;5.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.027\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e10.18\u0026plusmn;4.78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e9.58\u0026plusmn;4.44\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.464\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eFSH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e7.82\u0026plusmn;1.90\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e7.85\u0026plusmn;2.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.932\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e7.82\u0026plusmn;2.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e8.45\u0026plusmn;2.80\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.146\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eLH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e4.63\u0026plusmn;2.66\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e5.10\u0026plusmn;2.87\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.204\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e4.23\u0026plusmn;2.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e4.19\u0026plusmn;1.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.911\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eE2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e49.89\u0026plusmn;58.03\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e48.76\u0026plusmn;30.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.855\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e45.38\u0026plusmn;23.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e53.75\u0026plusmn;34.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.098\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eP\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e0.67\u0026plusmn;0.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e0.83\u0026plusmn;1.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.349\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e0.71\u0026plusmn;1.08\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e0.83\u0026plusmn;1.55\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.584\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003ePRL\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e22.78\u0026plusmn;54.34\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e19.84\u0026plusmn;26.58\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.607\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e22.02\u0026plusmn;34.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e19.48\u0026plusmn;27.97\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.658\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e1.03\u0026plusmn;5.52\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e0.93\u0026plusmn;4.61\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.889\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e1.01\u0026plusmn;3.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e0.54\u0026plusmn;0.73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.374\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAMH\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e3.48\u0026plusmn;2.07\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e4.03\u0026plusmn;2.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.069\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e3.08\u0026plusmn;2.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e2.87\u0026plusmn;1.74\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.610\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCOH protocol\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;GnRH-Agonist\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e24.04%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e31.30%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.231\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e32.53%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e23.08%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.238\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"32.05282112845138%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp;GnRH-Antagonist\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e75.96%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.647058823529413%\"\u003e\n \u003cp\u003e68.70%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e67.47%\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.3265306122449%\"\u003e\n \u003cp\u003e76.92%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTotal Gn dose (IU)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e2549.06\u0026plusmn;1026.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e2368.73\u0026plusmn;1028.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.196\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e2934.10\u0026plusmn;1155.65\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e3054.72\u0026plusmn;1178.62\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.559\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo. Oocytes retrieved\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e6.25\u0026plusmn;2.18\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e7.03\u0026plusmn;1.89\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.005\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e6.34\u0026plusmn;2.04\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e6.60\u0026plusmn;2.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.489\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"27.611168562564632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eEMT on the day of transfer (mm)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e11.54\u0026plusmn;2.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.201654601861428%\"\u003e\n \u003cp\u003e10.89\u0026plusmn;2.28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.037\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e10.67\u0026plusmn;2.30\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.064115822130299%\"\u003e\n \u003cp\u003e10.93\u0026plusmn;1.95\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"6.928645294725957%\"\u003e\n \u003cp\u003e0.509\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003eBMI, Body Mass Index; IVF, in vitro fertilization; AFC, antral follicle count; FSH, Follicle-Stimulating Hormone; LH, Luteinizing Hormone; E2, Estradiol; P, Progesterone; PRL, prolactin; T, testosterone; AMH, anti-mullerian hormone, COH, controlled ovarian hyperstimulation; Gn, Gonadotropin\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ctable align=\"\" border=\"1\" cellpadding=\"0\" cellspacing=\"0\" style=\"margin-right: calc(3%); width: 97%;\" width=\"100%\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"13\" style=\"width: 37.0642%;\" width=\"96.08333333333333%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 2. Pregnancy outcomes of first FET cycle (eSET versus DET)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0373%;\" width=\"15.333333333333334%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" style=\"width: 10.692%;\" width=\"28.833333333333332%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"1.3333333333333333%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"7\" style=\"width: 52.9255%;\" width=\"54.5%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0373%;\" width=\"16.81931723563697%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 3.041%;\" width=\"5.995004163197335%\"\u003e\n \u003cp\u003e\u003cstrong\u003eeSET\u003cbr\u003e\u0026nbsp;(N=104)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 3.041%;\" width=\"6.328059950041632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDET\u003cbr\u003e\u0026nbsp;(N=115)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" style=\"width: 7.3284%;\" width=\"16.48626144879267%\"\u003e\n \u003cp\u003e\u003cstrong\u003eunadjusted group difference\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"10.990840965861782%\"\u003e\n \u003cp\u003e\u003cstrong\u003eadjusted group difference*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 3.041%;\" width=\"6.328059950041632%\"\u003e\n \u003cp\u003e\u003cstrong\u003eeSET\u003cbr\u003e\u0026nbsp;(N=83)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" style=\"width: 3.041%;\" width=\"7.077435470441299%\"\u003e\n \u003cp\u003e\u003cstrong\u003eDET\u0026nbsp;\u003cbr\u003e\u0026nbsp;(N=52)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 4.9354%;\" width=\"13.40549542048293%\"\u003e\n \u003cp\u003e\u003cstrong\u003eunadjusted group difference\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" style=\"width: 13.1648%;\" width=\"13.40549542048293%\"\u003e\n \u003cp\u003e\u003cstrong\u003eadjusted group difference*\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"22.620380739081746%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"12.65397536394177%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u0026nbsp;\u003cbr\u003e\u0026nbsp;(95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"6.382978723404255%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"11.646136618141098%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u0026nbsp;\u003cbr\u003e\u0026nbsp;(95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"6.382978723404255%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"11.646136618141098%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u0026nbsp;\u003cbr\u003e\u0026nbsp;(95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"6.382978723404255%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"11.646136618141098%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR\u0026nbsp;\u003cbr\u003e\u0026nbsp;(95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"6.382978723404255%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"16.472545757071547%\"\u003e\n \u003cp\u003e\u003cstrong\u003ebiochemical pregnancy rate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.2337%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e65\u003c/p\u003e\n \u003cp\u003e(62.50%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e74\u003c/p\u003e\n \u003cp\u003e(64.35%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"9.40099833610649%\"\u003e\n \u003cp\u003e0.923\u003c/p\u003e\n \u003cp\u003e(0.532-1.602)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.777\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.663\u003c/p\u003e\n \u003cp\u003e(0.354-1.241)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.199\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e30\u003c/p\u003e\n \u003cp\u003e(36.14%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"7.071547420965058%\"\u003e\n \u003cp\u003e29\u003c/p\u003e\n \u003cp\u003e(55.77%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.449\u003c/p\u003e\n \u003cp\u003e(0.221-0.910)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.026\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.409\u003c/p\u003e\n \u003cp\u003e(0.189-0.888)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.024\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"16.472545757071547%\"\u003e\n \u003cp\u003e\u003cstrong\u003eclinical pregnancy rate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.2337%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e59\u003c/p\u003e\n \u003cp\u003e(56.73%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e71\u003c/p\u003e\n \u003cp\u003e(61.74%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"9.40099833610649%\"\u003e\n \u003cp\u003e0.813\u003c/p\u003e\n \u003cp\u003e(0.473-1.395)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.451\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.585\u003c/p\u003e\n \u003cp\u003e(0.315-1.089)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.091\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003cp\u003e(33.73%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"7.071547420965058%\"\u003e\n \u003cp\u003e24\u003c/p\u003e\n \u003cp\u003e(50.00%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.509\u003c/p\u003e\n \u003cp\u003e(0.251-1.034)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.062\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.473\u003c/p\u003e\n \u003cp\u003e(0.219-1.019)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.056\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"16.472545757071547%\"\u003e\n \u003cp\u003e\u003cstrong\u003eongoing pregnancy rate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.2337%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e50\u003c/p\u003e\n \u003cp\u003e(48.08%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e64\u003c/p\u003e\n \u003cp\u003e(55.65%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"9.40099833610649%\"\u003e\n \u003cp\u003e0.738\u003c/p\u003e\n \u003cp\u003e(0.433-1.256)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.263\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.614\u003c/p\u003e\n \u003cp\u003e(0.335-1.123)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.113\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003cp\u003e(20.48%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"7.071547420965058%\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003cp\u003e(38.46%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.412\u003c/p\u003e\n \u003cp\u003e(0.190-0.892)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.024\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.358\u003c/p\u003e\n \u003cp\u003e(0.155-0.828)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"16.472545757071547%\"\u003e\n \u003cp\u003e\u003cstrong\u003elive birth rate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.2337%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003cp\u003e(46.15%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e60\u003c/p\u003e\n \u003cp\u003e(52.17%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"9.40099833610649%\"\u003e\n \u003cp\u003e0.786\u003c/p\u003e\n \u003cp\u003e(0.462-1.337)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.374\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.622\u003c/p\u003e\n \u003cp\u003e(0.340-1.140)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.124\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e17\u003c/p\u003e\n \u003cp\u003e(20.48%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"7.071547420965058%\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003cp\u003e(38.46%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.412\u003c/p\u003e\n \u003cp\u003e(0.190-0.892)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.024\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e0.358\u003c/p\u003e\n \u003cp\u003e(0.155-0.828)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.016\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd style=\"width: 11.0372%;\" width=\"16.472545757071547%\"\u003e\n \u003cp\u003e\u003cstrong\u003emultiple birth rate (%)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 8.2337%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e12/60\u003c/p\u003e\n \u003cp\u003e(20.00%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"9.40099833610649%\"\u003e\n \u003cp\u003e\u0026nbsp;/\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.001\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e/\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.8387%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e/\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"6.322795341098169%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 3.041%;\" width=\"7.071547420965058%\"\u003e\n \u003cp\u003e4/20\u003c/p\u003e\n \u003cp\u003e(20.00%)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e\u0026nbsp;/\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.5425%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e0.155\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 2.3929%;\" width=\"8.6522462562396%\"\u003e\n \u003cp\u003e\u0026nbsp;/\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd style=\"width: 6.7819%;\" width=\"4.7420965058236275%\"\u003e\n \u003cp\u003e/\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"13\" style=\"width: 99.867%;\"\u003e\u003cbr\u003e* Adjusted for age, BMI, indications for IVF, AFC, EMT, No. oocytes retrieved.\u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003ctable border=\"1\" cellpadding=\"0\" cellspacing=\"0\" width=\"1103\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"10\" width=\"100%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTable 3. Logistic regression analysis on the live birth rate in patients with unexpected poor prognosis\u003c/strong\u003e\u003cstrong\u003e.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.02536231884058%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" width=\"28.985507246376812%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 1\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.880434782608695%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.880434782608695%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"4\" width=\"37.22826086956522%\"\u003e\n \u003cp\u003e\u003cstrong\u003eGroup 2\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.041704442429737%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" width=\"18.404351767905712%\"\u003e\n \u003cp\u003e\u003cstrong\u003eunivariate analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" width=\"18.495013599274706%\"\u003e\n \u003cp\u003e\u003cstrong\u003emultivariate analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.887579329102448%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" width=\"18.5856754306437%\"\u003e\n \u003cp\u003e\u003cstrong\u003eunivariate analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" width=\"18.5856754306437%\"\u003e\n \u003cp\u003e\u003cstrong\u003emultivariate analysis\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR (95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR (95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u003cstrong\u003e \u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR (95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003ep\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;value\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e\u003cstrong\u003eOR (95% CI)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u003cem\u003eP\u0026nbsp;\u003c/em\u003e\u003c/strong\u003e\u003cstrong\u003evalue\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eage\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e0.959\u003c/p\u003e\n \u003cp\u003e(0.869-1.059)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.409\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e0.959\u003c/p\u003e\n \u003cp\u003e(0.869-1.059)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.409\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.759\u003c/p\u003e\n \u003cp\u003e(0.624-0.922)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.006\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.751\u003c/p\u003e\n \u003cp\u003e(0.605-0.932)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.009\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eBody Mass Index / BMI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e0.969\u003c/p\u003e\n \u003cp\u003e(0.887-1.059)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.490\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e0.969\u003c/p\u003e\n \u003cp\u003e(0.887-1.059)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.490\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.900\u003c/p\u003e\n \u003cp\u003e(0.769-1.053)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.188\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.939\u003c/p\u003e\n \u003cp\u003e(0.793-1.113)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.471\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eAFC\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e0.986\u003c/p\u003e\n \u003cp\u003e(0.936-1.039)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.598\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e0.986\u003c/p\u003e\n \u003cp\u003e(0.936-1.039)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.598\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e1.042\u003c/p\u003e\n \u003cp\u003e(0.963-1.128)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.302\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e1.017\u003c/p\u003e\n \u003cp\u003e(0.932-1.110)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.699\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eendometrial thickness\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e1.004\u003c/p\u003e\n \u003cp\u003e(0.894-1.127)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.948\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e1.004\u003c/p\u003e\n \u003cp\u003e(0.894-1.127)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.948\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e1.082\u003c/p\u003e\n \u003cp\u003e(0.907-1.291)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.381\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e1.020\u003c/p\u003e\n \u003cp\u003e(0.836-1.246)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.842\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo. oocytes retrieved\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e1.076\u003c/p\u003e\n \u003cp\u003e(0.945-1.226)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.266\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e1.076\u003c/p\u003e\n \u003cp\u003e(0.945-1.226)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.266\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e1.007\u003c/p\u003e\n \u003cp\u003e(0.841-1.207)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.939\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.979\u003c/p\u003e\n \u003cp\u003e(0.807-1.187)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.827\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.009049773755656%\"\u003e\n \u003cp\u003e\u003cstrong\u003eNo. transferred embryos\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.497737556561086%\"\u003e\n \u003cp\u003e0.786\u003c/p\u003e\n \u003cp\u003e(0.462-1.337)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.374\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.588235294117647%\"\u003e\n \u003cp\u003e0.786\u003c/p\u003e\n \u003cp\u003e(0.462-1.337)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.374\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e \u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.412\u003c/p\u003e\n \u003cp\u003e(0.190-0.892)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.024\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"10.76923076923077%\"\u003e\n \u003cp\u003e0.367\u003c/p\u003e\n \u003cp\u003e(0.161-0.840)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"7.873303167420814%\"\u003e\n \u003cp\u003e0.018\u0026nbsp;\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"embryo transfer strategy, Poseidon criteria, low prognosis, live birth rate, multiple birth rate","lastPublishedDoi":"10.21203/rs.3.rs-2752135/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-2752135/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003eBackground: \u003c/strong\u003eThe 2016 Patient-Oriented Strategy Encompassing IndividualizeD Oocyte Number (POSEIDON) criteria redefined the poor responders as low prognosis patients. The embryo transfer strategy for Poseidon patients remained to be addressed. This study aimed to investigate the optimized number of embryos to transfer for unexpected low-prognosis patients (Poseidon Group 1 and Group 2) with blastocyst transfer in their first frozen cycle.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods: \u003c/strong\u003eA retrospective cohort study of 2970 patients who underwent frozen-thawed embryo transfer (FET) between January 2018 and December 2021. Patients from Poseidon Group 1 (N=219) and Group 2 (N=135) who underwent blastocyst transfer in their first FET cycles were included and divided into the elective single embryo transfer (eSET) group and the double embryo transfer (DET) group.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults: \u003c/strong\u003eFor Poseidon Group 1, the live birth rateper embryo transfer of the DET group was slightly higher than the eSET group (52.17% vs 46.15%, OR 0.786, 95% CI 0.462-1.337, \u003cem\u003eP\u003c/em\u003e = 0.374; adjusted OR (aOR) 0.622, 95% CI 0.340-1.140, \u003cem\u003eP\u003c/em\u003e = 0.124), while a significant increase of 20.00% in the multiple birth rate was shown. For Group 2, higher live birth rates were observed in the DET group compared to the eSET group (38.46% vs 20.48%, OR 0.412, 95% CI 0.190-0.892, \u003cem\u003eP\u003c/em\u003e = 0.024; aOR 0.358, 95% CI 0.155-0.828, \u003cem\u003eP\u003c/em\u003e = 0.016). The difference in the multiple birth rate was 20.00% without statistical significance. Univariate and multivariate analyses revealed that age (OR 0.759, 95% CI .624-0.922, \u003cem\u003eP\u003c/em\u003e = 0.006 and OR 0.751, 95% CI 0.605-0.932, \u003cem\u003eP\u003c/em\u003e = 0.009) and the number of transferred embryos (OR 0.412, 95% CI 0.190-0.892, \u003cem\u003eP\u003c/em\u003e = 0.024 and OR 0.367, 95% CI 0.161-0.840, \u003cem\u003eP\u003c/em\u003e= 0.018) were significant variables for the live birth rate in Poseidon Group 2.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions: \u003c/strong\u003eThe findings in the present study showed that eSET was preferred in the first frozen cycle for Poseidon Group 1 to avoid unnecessary risks. Double embryo transfer strategy could be considered to improve the success rate for Poseidon Group 2 with caution. Further stratification by age is needed for a more scientific discussion about the embryo transfer strategy for Poseidon patients.\u003c/p\u003e","manuscriptTitle":"What is the Optimal Number of Embryos to Transfer for Poseidon Group 1 and Group 2? A retrospective study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2023-03-31 15:17:55","doi":"10.21203/rs.3.rs-2752135/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"9ae023bb-80e2-4c36-a5ec-13097a78aa68","owner":[],"postedDate":"March 31st, 2023","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2023-03-31T15:17:58+00:00","versionOfRecord":[],"versionCreatedAt":"2023-03-31 15:17:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-2752135","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-2752135","identity":"rs-2752135","version":["v1"]},"buildId":"7rjqhiLT3MXkJMwkYKINL","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}