Comparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women

Comparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women Pınar Tuğçe Özer, Kevser Arkan, Sedat Akgöl, Sercan Kantarcı, and 6 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8234858/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 11 You are reading this latest preprint version Abstract Purpose To compare body mass index (BMI) and abdominal subcutaneous fat thickness (ASFT) in predicting the success of oxytocin-induced labor and cumulative oxytocin requirement in term pregnancies. Methods We performed a prospective cohort study of 193 term singleton gravidas induced with oxytocin at a tertiary center in Turkey. ASFT was measured by standardized ultrasound before infusion. Primary outcomes were cumulative oxytocin dose and delivery mode; secondary outcomes included labor durations. Group comparisons used ANOVA/Kruskal–Wallis with post-hoc tests. Determinants of oxytocin dose and labor duration were analyzed by univariate and stepwise multivariable regression (p<0.05). Results Higher BMI was associated with longer first-stage and total labor (both p<0.001), without a significant difference in oxytocin dose across BMI groups. Increasing ASFT tertiles were associated with longer first-stage and total labor (both p<0.001). In univariate analyses, ASFT (β=1.73, p=0.001) and Bishop score=1 vs 0 (β=1.98, p=0.013) predicted higher oxytocin dose. In multivariable models, ASFT (β=1.59, p=0.002) and Bishop score=1 (β=2.84, p=0.008) independently predicted oxytocin dose (R²=0.09). For total labor duration, the multivariable model identified active-phase duration (β=0.80, p<0.001), BMI (β=11.51, p<0.001), oxytocin dose (β=4.88, p=0.008), amniotomy (β=38.25, p=0.013), and parity (β=-14.56, p=0.002) as significant (R²=0.49). Neonatal Apgar scores were similar across groups. Conclusions Both BMI and ASFT relate to prolonged labor, but ASFT is an independent predictor of cumulative oxytocin requirement, whereas BMI is not. Incorporating ASFT—alongside cervical status—may improve individualized induction planning, particularly in populations with high obesity prevalence. Prospective multicenter studies are warranted. Abdominal subcutaneous fat thickness Body mass index Labor induction. Oxytocin-induced labor Figures Figure 1 Figure 2 Figure 3 Figure 4 Introduction Labor induction is a common obstetric intervention to achieve vaginal delivery. Identifying and optimizing factors that influence its success can enhance the childbirth experience. However, predicting induction success remains challenging due to the heterogeneity and interplay of multiple maternal and fetal variables, making comparisons across studies difficult [1]. Obesity is among the key factors that may influence induction outcomes. In the United States, over 50% of women aged 20–39 are overweight or obese, posing significant challenges for obstetric care. Although studies directly comparing induction methods in obese women are limited, existing data suggest that higher body mass index (BMI) is associated with reduced induction success. However, BMI alone may not accurately reflect body fat distribution. Abdominal subcutaneous fat thickness (ASFT) may affect metabolic pathways and, in turn, influence induction outcomes [2]. To contribute to the existing body of knowledge, this study aimed to compare body mass index (BMI) and abdominal subcutaneous fat thickness (ASFT) in predicting the success of labor induction. The findings may support the development of more effective induction strategies in obese pregnant women. MATERIAL AND METHODS Study Design and Participants This prospective cohort study was carried out at Diyarbakır Gazi Yaşargil Training and Research Hospital, Turkey. Institutional ethical approval was obtained prior to data collection (Approval No: 2024/07–23). The study included 193 term singleton pregnancies admitted for labor induction with oxytocin between 2024/06-2025/06. Informed consent was obtained from all individual participants included in the study. Women with multiple gestations, major fetal anomalies, elective cesarean section without labor attempt, or missing medical or ultrasonographic data were excluded from the analysis. Relevant maternal information—such as age, gravidity, parity, pre-pregnancy body weight, gestational weight gain, height, BMI, and gestational age at admission—was extracted from electronic health records. Ultrasonographic Assessment of ASFT At the time of hospital admission for delivery and prior to initiation of oxytocin infusion, abdominal subcutaneous fat thickness (ASFT) was assessed by a single trained obstetrician using transabdominal ultrasonography with a curvilinear probe (4–8 MHz, GE Healthcare). All measurements were performed in accordance with standardized scanning protocols to ensure consistency. The measurement technique was based on a validated method previously described by Pétursdóttir Maack et al [ 3 ]. Scans were obtained in the longitudinal plane with careful attention to apply minimal probe pressure to avoid compression of the subcutaneous tissue. During each assessment, the skin surface, linea alba, rectus abdominis muscle, umbilicus, and iliac crests were identified as anatomical landmarks to optimize visualization. ASFT was defined as the perpendicular distance from the outer skin surface to the anterior margin of the rectus abdominis muscle. The measurement point was standardized at the intersection of a horizontal line drawn between the most superior points of the bilateral iliac crests and the midline linea alba. For reliability, three independent measurements were obtained for each patient, and the mean value (in millimeters) was recorded. All ultrasonographic examinations were performed by the same operator, thereby minimizing inter-observer variability and enhancing reproducibility. Study Outcomes The primary outcome measures were: Total cumulative oxytocin dose administered during the induction process (mU), Mode of delivery following induction (vaginal vs. cesarean), Labor duration , specifically time intervals from the start of oxytocin to active labor and to delivery. Data The median age of participants was 27 years (IQR = 9), with a height of 158 cm (IQR = 8), weight of 72 kg (IQR = 16), and BMI of 28.52 (IQR = 5.58). Pre-pregnancy weight and BMI were 61.5 kg (IQR = 14) and 24.22 (IQR = 5.13), while gestational weight gain was 10 kg (IQR = 5). Median abdominal subcutaneous fat thickness (ASFT) was 1.57 cm (IQR = 0.79). Gravidity and parity were 3 (IQR = 3) and 1 (IQR = 3), respectively. At delivery, the median gestational age was 38.5 weeks (IQR = 1.9). The oxytocin dose had a median of 5 units (IQR = 5), with a maximum of 45 units (IQR = 35). Induction lasted 130 minutes (IQR = 168), the active phase 104 minutes (IQR = 105), and the first and second labor stages 300 (IQR = 165) and 20 minutes (IQR = 22), respectively, for a total duration of 323 minutes (IQR = 165). Median birth weight was 3,100 g (IQR = 520), and Apgar scores were 8 and 9 at the 1st and 5th minutes. Categorical data showed 69.43% of participants in Bishop Score group 2, 17.10% in group 1, and 13.47% in group 0. Amniotomy was performed in 52.85% of cases. BMI was classified into three groups ( 1.8). Bishop scores were dichotomized as < 6 (group 1) and ≥ 6 (group 2). The study outcomes were oxytocin dose in relation to clinical variables and total labor duration, particularly its association with oxytocin use while adjusting for covariates. Statistical Methodology Normally distributed variables were compared using ANOVA with Tukey’s HSD or Games-Howell post-hoc tests, depending on variance homogeneity. Non-normally distributed variables were analyzed with the Kruskal-Wallis test, followed by Dunn’s pairwise comparisons. Significance was set at p < 0.05. For regression, univariate, full multivariate, and stepwise models were applied to examine associations with labor duration, adjusting for demographic and clinical covariates. Marginal effects plots were generated to illustrate adjusted associations. Normality of continuous variables was assessed using the Shapiro–Wilk test. Post-hoc pairwise comparisons were adjusted using Bonferroni correction to control for multiple testing. Programming Environment All of the steps carried out in the study were run in Python 3.12.1. The packages used in the analyses were numpy 1.26.3, pandas 2.0.3, statsmodels 0.14.2, scipy 1.12.0 and matplotlib 3.8.3. RESULTS Women were stratified into three groups based on pre-pregnancy BMI, and their baseline characteristics and labor outcomes are summarized in Table 1. Maternal age and parity tended to be higher in the highest BMI category (Group 3) compared to the lowest (Group 1). In particular, Group 3 mothers were older on average (29.1 vs 24.9 years, p = 0.003) and had a greater median parity (2 vs 1, p = 0.032) than those in Group 1. As expected, pre-pregnancy weight and BMI differed significantly across the groups (p < 0.001 for both), with Group 3 women weighing approximately 27 kg more than Group 1 on average at the start of pregnancy. Gestational weight gain was also higher in the obese group (median 12.0 kg in Group 3 vs 8.0 kg in Group 1, p 0.05). Newborn outcomes were similar across BMI categories: the 1-minute and 5-minute Apgar scores had medians of 8 and 9, respectively, in all groups. A slight difference in 5-minute Apgar reached nominal significance (p = 0.049), though median values were identical (9 in each group). Importantly, neonatal birth weight increased with maternal BMI (median 3200 g in Group 3 vs 2950 g in Group 1, p < 0.001). Labor process measures showed notable variation by BMI category (Table 1). The duration of the first stage of labor was significantly prolonged in high-BMI women. Group 3 experienced a median first-stage labor of 416.5 minutes, compared to approximately 281 minutes in Groups 1 and 2 (p < 0.001 for Group 3 vs. both Group 1 and 2). Consistently, the total labor duration (from induction to delivery) was longest in Group 3 (median 452 minutes) and significantly greater than in the lower BMI groups (medians ~ 300 minutes; p < 0.001). In contrast, the second stage of labor did not differ appreciably by BMI (median ~ 20 minutes in all groups, p = 0.800). Likewise, the induction-to-active labor interval and the total oxytocin dose required for induction were not significantly different among BMI groups (p = 0.913 and p = 0.985, respectively). Maximum oxytocin infusion rates and the duration of oxytocin administration in active labor were similar across the BMI categories (p = 0.528 and p = 0.349). The rate of amniotomy was also comparable (approximately 50% in each group, p = 0.595). As an expected consequence of adiposity, Table 1 shows that women in the highest BMI group had significantly greater abdominal subcutaneous fat thickness (ASFT). The median ASFT in Group 3 was 1.92 cm versus 1.35 cm in Group 1 (p < 0.001), and a majority (58.6%) of obese women fell into the highest ASFT category, compared to only 15.2% in the low-BMI group. Despite these differences, the distribution of Bishop score categories at induction was similar among BMI groups (p = 0.380), indicating that initial cervical favorability did not differ by maternal BMI. Stratification by ASFT yielded similar trends (Table 2). Women with the greatest subcutaneous fat thickness (ASFT Group 3) tended to have higher BMI and weight, as the two measures were strongly correlated. Median BMI in ASFT Group 3 was 31.5, significantly higher than in Group 1 (26.8; p < 0.001). ASFT Group 3 also had a higher proportion of obese patients (64% were BMI Group 3) compared to Group 1 (13.9%; p < 0.001). Maternal height showed a small but significant difference across ASFT groups (p = 0.017), with Group 2 being slightly taller on average than the others (median 161 cm vs 158 cm in Group 1). No significant differences were observed in maternal age, parity, or gravidity by ASFT category (p > 0.05). In terms of labor outcomes, a higher ASFT was associated with a longer labor course. The median first-stage labor duration increased from 279 minutes in ASFT Group 1 to 372 minutes in Group 3 (p < 0.001). Total labor time followed the same pattern, with Group 3 having the longest median duration (~ 399.5 minutes) compared to ~ 291 minutes in Group 1 (p < 0.001). Consequently, women in the highest ASFT category required more time to deliver after induction. However, other induction and delivery parameters were not significantly influenced by subcutaneous fat thickness. There were no differences among ASFT groups in second-stage duration, induction duration, or the need for oxytocin. The median total oxytocin dose was approximately 5–6 units in all ASFT groups, and this did not vary significantly (p = 0.713*). Similarly, the maximum oxytocin dose and the duration of oxytocin use in active labor were not significantly different, though the latter showed a trend toward increase with ASFT (median 120 minutes in Group 3 vs 90 minutes in Group 1, p = 0.053). Newborn outcomes remained consistent: Apgar scores were uniformly high (median 8 and 9 at 1 and 5 minutes, respectively, p > 0.90) regardless of maternal fat thickness, and median birth weight was slightly greater in the highest ASFT group (3200 g vs 3000 g in lowest, p = 0.030). When grouped by initial Bishop score (cervical favorability), most clinical characteristics and outcomes did not differ significantly (Table 3). Maternal BMI and ASFT showed no clear trend across Bishop score categories; for instance, median BMI ranged from ~ 28 to 30 with p = 0.353. An exception was observed in the intermediate Bishop category (Group 1), which had a higher median ASFT (1.89 cm) compared to the favorable Bishop group (1.50 cm in Group 2, p = 0.010 for Group 1 vs 2). Gestational weight gain was also slightly higher in women with a Bishop score of 1 (median 12.0 kg) versus those with an unfavorable cervix (9.5 kg in Group 0, p = 0.025). Despite these differences, parity and gravidity were similar across Bishop groups, as were maternal age and gestational age at delivery (all p > 0.4). Labor progression metrics showed no major variation by Bishop score category in this cohort. Neither the first-stage nor total labor durations were significantly different among Bishop Groups 0, 1, and 2 (p = 0.387 and p = 0.412, respectively). Notably, however, the total amount of oxytocin required for induction was higher in women with a moderately favorable cervix (Bishop Group 1) compared to those with an unfavorable cervix. The median oxytocin dose in Group 1 was 10 units, versus 5 units in Group 0 (p = 0.029*). Women with a favorable Bishop (Group 2) required a similar oxytocin amount as the unfavorable group (median 5 units), suggesting that the Group 1 patients paradoxically needed the most oxytocin. Rates of amniotomy were not significantly different between Bishop categories (p = 0.052), although there was a trend toward fewer amniotomies in the lowest Bishop group. Newborn Apgar scores and birth weights did not vary with Bishop score, remaining consistent across groups (all medians 8/9 for Apgars, p > 0.4; median birth weight ~ 3100 g, p = 0.939). These findings indicate that, aside from a slightly higher oxytocin requirement in the intermediate Bishop group, initial cervical readiness was not strongly associated with labor duration or other outcomes in our sample. We next examined predictors of oxytocin requirement using linear regression analyses (Tables 4 and 5). In univariate models, maternal abdominal fat thickness (ASFT) and Bishop score category showed significant relationships with the total oxytocin dose needed for induction. Each 1 cm increase in ASFT was associated with an estimated 1.73-unit increase in oxytocin consumption (p = 0.001) in the unadjusted analysis. Likewise, having a Bishop score in Group 1 (moderately favorable) was linked to a higher oxytocin requirement, with women in this category needing approximately 2 units more oxytocin than those in Bishop Group 0 (p = 0.013). In contrast, most other maternal factors — including BMI, weight, age, parity, and gestational weight gain — were not significantly associated with oxytocin dose on their own (p > 0.05). The total duration of labor showed a positive correlation with oxytocin dose in univariate analysis (p = 0.006), and a higher maximum oxytocin infusion rate exhibited a trend toward significance (p = 0.087), suggesting that more prolonged or intensive inductions tended to use larger oxytocin amounts. Multivariate regression confirmed that ASFT and Bishop score were independent predictors of oxytocin requirement (Table 5). In the final stepwise model, only these two variables remained statistically significant. Controlling for other factors, each additional 1 cm of abdominal fat thickness was associated with a 1.59-unit increase in the oxytocin dose (p = 0.002). Similarly, women with a Bishop score of 1 required on average 2.84 more oxytocin units than those with an unfavorable Bishop score (Group 0) (p = 0.008). A favorable Bishop (Group 2) was not significantly different from Group 0 in oxytocin needs after adjustment. This model’s R² was 0.09, indicating that about 9% of the variance in oxytocin dose was explained by maternal ASFT and Bishop score. Figure 1 illustrates the positive association between ASFT and oxytocin requirement. The marginal effect plot shows that higher maternal fat thickness corresponds to higher predicted oxytocin doses, with the regression line sloping upward. The observed data points generally align with this trend, although considerable individual variability is evident. Thus, while greater maternal subcutaneous fat and a mid-range Bishop score each contribute to higher oxytocin utilization, much of the variation in oxytocin requirement remains unexplained by these factors alone. Finally, we analyzed factors associated with the total duration of labor. Table 6 presents univariate regression results for labor duration (measured from induction start to delivery). Several maternal characteristics and induction parameters showed significant unadjusted associations with how long labor lasted. Notably, indices of maternal adiposity were strong predictors: each 1 kg increase in maternal weight was associated with an approximately 3.14-minute longer labor (p < 0.001), and each 1 unit increase in BMI corresponded to about 9.7 extra minutes of labor (p < 0.001). Abdominal fat thickness had an even more pronounced effect size; an increase of 1 cm in ASFT was linked to an 81-minute prolongation of labor on average (p < 0.001). In addition, greater oxytocin requirements signaled longer labors. For every 1 unit increase in total oxytocin dose, labor duration increased by about 6.8 minutes (p = 0.006*). Likewise, each 1 mU/min higher in the maximum oxytocin infusion rate was associated with a 3.43-minute longer labor (p < 0.001). The length of the oxytocin-active phase of labor and the overall induction time were also strongly correlated with total labor duration: essentially, the longer a patient remained on oxytocin or waited for active labor, the longer the total time to delivery (p < 0.001 for both). On the other hand, obstetric history factors had the expected protective effect. Multiparous women labored for a significantly shorter time than primiparous women. Each additional prior birth was associated with about a 15-minute reduction in labor duration (p = 0.010), and each increment in gravidity showed a similar trend (p = 0.036). Variables such as maternal age, height, gestational age, and infant birth weight were not significant predictors of labor length in the univariate analysis (p > 0.3). Performing an amniotomy was associated with a trend toward longer labor (+ 38 minutes on average, p = 0.066), but this did not reach statistical significance at the 0.05 level in univariate testing. The multivariable analysis identified five independent predictors of total labor duration (Table 7). In the final adjusted model (built via stepwise selection), the duration of oxytocin administration during active labor emerged as the strongest predictor of total labor time. Holding other factors constant, each additional minute of oxytocin use in active labor was associated with an increase of 0.80 minutes in the overall labor duration (p < 0.0001). Maternal BMI remained independently associated with labor length: for each 1-point increase in BMI, total labor was prolonged by about 11.5 minutes on average (p < 0.001), after adjusting for other variables. Parity continued to have a significant inverse relationship with labor duration; each additional birth shortened the labor by roughly 14.6 minutes (p = 0.002). The total amount of oxytocin administered also retained significance in the multivariate model – even when accounting for the length of oxytocin use, a higher cumulative oxytocin dose predicted a longer labor (approximately + 4.88 minutes per unit, p = 0.008). Lastly, amniotomy was an independent factor: having an amniotomy performed was associated with an increase of about 38 minutes in total labor time compared to no amniotomy (p = 0.013). Together, these five factors explained nearly half of the variability in labor duration (model R² = 0.49, overall p < 0.0001), indicating a moderate goodness-of-fit. The influence of key predictors on labor length is further illustrated in Figs. 2–4. Figure 2 shows the marginal effect of the oxytocin active phase duration on total labor time, demonstrating a clear positive linear trend – patients who required longer periods of oxytocin infusion experienced correspondingly longer labors. Similarly, Fig. 3 depicts a positive association between maternal BMI and labor duration when other factors are held constant; higher BMI values are linked with progressively longer induction-to-delivery intervals. Figure 4 highlights the relationship between total oxytocin dose and labor length, indicating that cases in which a larger amount of oxytocin was administered generally had prolonged labor courses. In all these plots, the observed data points align with the upward-sloping regression lines, though some degree of scatter is present. These findings underscore that greater maternal adiposity and higher oxytocin requirements are associated with longer induced labor, whereas multiparity tends to shorten it. Each significant predictor contributes to the duration of labor, and the multivariate model confirms that a combination of maternal factors and intervention-related factors jointly determine the length of induced labor in our cohort. DISCUSSION This study investigated the effects of maternal BMI and anterior subcutaneous fat thickness (ASFT) on oxytocin requirements and total labor duration in term singleton pregnancies undergoing labor induction. Our findings suggest that both BMI and ASFT influence labor-related parameters, with ASFT appearing to be a more sensitive predictor of oxytocin need. In our study, patients with higher BMI and ASFT values had significantly longer total and first-stage labor durations, particularly in BMI ≥ 30 kg/m² and ASFT ≥ 2.2 cm groups. These results align with previous findings suggesting that obesity may prolong both latent and active labor phases, contributing to dystocia. A large French cohort of over 7,500 term pregnancies also reported prolonged labor in nulliparous obese women (HR: 0.75; 95% CI: 0.64–0.88), with no such association in multiparas, indicating potentially slower uterine contractility and cervical progression in obese nulliparas [ 4 ]. A recent analysis involving over 35,000 births found shorter time to full cervical dilation in nulliparous women compared to the cohort reported by Zhang et al., which included more than 62,000 cases. The authors attributed this difference to a more homogeneous ethnic composition (94% White) and a lower mean pre-pregnancy BMI (21.8 vs. 23.4 kg/m²) in their cohort. These findings indirectly support previous studies linking higher BMI with prolonged labor duration [ 5 ]. Epidemiological data suggest that maternal adiposity influences the labor process not only through mechanical factors but also via biochemical mechanisms [ 6 ]. Carlson et al. (2020) showed that obesity-related metabolic pathways may impair uterine contractility via endocrine and inflammatory mechanisms. Lipid accumulation and altered myometrial signaling may contribute to labor dystocia in obese women [ 6 ]. Chen et al. (2020) found that pre-pregnancy overweight and obesity increased the risk of maternal and fetal complications, underscoring the need to address obesity before conception [ 7 ]. Abdominal subcutaneous fat thickness (ASFT) has been associated not only with delivery outcomes but also with metabolic and inflammatory changes during pregnancy. In a study by Eley et al. (2020), second-trimester SCFT showed stronger associations with cesarean delivery, gestational diabetes, and hypertension than BMI. Other studies have also linked elevated SCFT with increased CRP and HbA1c levels, suggesting a potential role in systemic inflammation and metabolic stress that may indirectly influence labor [ 8 , 9 ]. In this study, ASFT was identified as a significant and independent predictor of oxytocin requirement, regardless of maternal BMI. Increasing ASFT values were associated with a linear rise in cumulative oxytocin dose. Additionally, evaluating ASFT alongside cervical parameters such as the Bishop score may enhance the prediction of oxytocin sensitivity and induction success. Similarly, a study by Carlson et al. in nulliparous women with spontaneous labor found a significant association between maternal BMI and oxytocin requirement, with BMI accounting for approximately 16.5% of the variance in hourly oxytocin dose. These findings suggest that while BMI may partially influence uterine contractility and oxytocin sensitivity, it may not fully reflect local soft tissue characteristics, such as those represented by ASFT [ 6 ]. In a prospective study by De Tina et al., oxytocin pharmacokinetics were evaluated in obese and non-obese pregnant women. While no significant differences were found in plasma oxytocin levels, the obese group had significantly lower plasma oxytocinase concentrations [ 10 ]. This finding suggests that oxytocin metabolism may be influenced not only by circulating concentrations but also by tissue-level receptor responses and local enzymatic activity. The strong association observed in our study between ASFT and oxytocin requirement highlights the specific impact of local soft tissue thickness on uterine contractility—beyond the commonly used BMI-based assessments. These findings support ASFT as a practical and feasible biometric parameter for predicting induction success. Despite prolonged labor duration and increased oxytocin use in patients with elevated BMI and ASFT, neonatal outcomes did not differ significantly between groups. This suggests that appropriate clinical management strategies, including timely oxytocin adjustment and close fetal monitoring, may help preserve fetal outcomes. However, prolonged labor may increase the risk of maternal complications such as fatigue, infection or cesarean delivery [ 11 ]. This study did not include maternal complications, which should be addressed in future research. Given the rising prevalence of obesity, incorporating maternal adipose tissue parameters into labor induction protocols may enhance clinical outcomes. Routine assessment of ASFT could support a more individualized approach to oxytocin management, particularly in high-risk populations. The strengths of our study include an adequate sample size, the inclusion of ASFT—a relatively underexplored parameter—and the use of regression analyses to evaluate potential confounders in detail. However, its prospective and single-center design, along with the exclusion of factors such as fetal position, contractility patterns, and provider variability, limit causal inferences. In addition, ASFT was measured only once before delivery, without accounting for its variation throughout pregnancy. In conclusion, both BMI and ASFT were associated with prolonged total labor duration; however, ASFT was also independently linked to increased oxytocin requirements. Incorporating ASFT into the antenatal assessment may improve labor management, particularly in populations with high obesity prevalence. Prospective, multicenter studies are needed to validate these findings. Declarations Funding The authors declare that no funds, grants, or other financial support were received during the preparation of this manuscript. Competing Interests The authors have no relevant financial or non-financial interests to disclose. Author Contributions All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Pınar Tuğçe Özer, Kevser Arkan, Sedat Akgöl, Sercan Kantarcı, Adnan Budak, Alper İleri, Mehmet Özer, Meriç Balıkoğlu, Mesut Ali Halisçelik, and Şeyhmus Tunç. The first draft of the manuscript was written by Pınar Tuğçe Özer, and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript. Ethics Approval This study was designed as a prospective observational cohort study. It was conducted in accordance with the principles of the Declaration of Helsinki. Ethical approval was obtained from the Diyarbakır Gazi Yaşargil Training and Research Hospital Clinical Research Ethics Committee (Approval No: 2024/07-23). Consent to Participate Informed written consent was obtained from all individual participants included in the study. Consent to Publish This manuscript contains no individual person’s data in any form (including images, identifiable details, or videos). Therefore, consent to publish is not applicable. Clinical Trial Registration Clinical trial number: not applicable. Our study is a non-interventional observational cohort study and did not require clinical trial registration. Availability of Data and Materials The datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request. References Batinelli L, Serafini A, Nante N, et al. Induction of labour: clinical predictive factors for success and failure. 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AJP Rep. 2020;10:E68–77. https://doi.org/10.1055/s-0040-1702928 . Chen CN, Chen HS, Hsu HC. Maternal prepregnancy body mass index, gestational weight gain, and risk of adverse perinatal outcomes in Taiwan: A population-based birth cohort study. Int J Environ Res Public Health. 2020;17. https://doi.org/10.3390/ijerph17041221 . Eley V, Sekar R, Chin A, et al. Increased maternal abdominal subcutaneous fat thickness and body mass index are associated with increased cesarean delivery: A prospective cohort study. Acta Obstet Gynecol Scand. 2019;98:196–204. https://doi.org/10.1111/aogs.13486 . Köşüş N, Koş̧̈̈us A, Turhan N. Relation between abdominal subcutaneous fat tissue thickness and inflammatory markers during pregnancy. Archives Med Sci. 2014;10:739–45. https://doi.org/10.5114/aoms.2014.44865 . De Tina A, Juang J, McElrath TF, et al. Oxytocin and Oxytocinase in the Obese and Nonobese Parturients during Induction and Augmentation of Labor. AJP Rep. 2019;9:E177–84. https://doi.org/10.1055/s-0039-1692196 . Pergialiotis V, Bellos I, Antsaklis A, et al. Maternal and neonatal outcomes following a prolonged second stage of labor: A meta-analysis of observational studies. Eur J Obstet Gynecol Reproductive Biology. 2020;252:62–9. Tables Tables are available in the Supplementary Files section. Additional Declarations No competing interests reported. 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Özer","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA20lEQVRIiWNgGAWjYDACZjB5gIGBvQFIG1gQpYWxAayF5wBIiwRR9kC1SCSAOERoMWfnPf6Y59cdefOZz69u+FEgwcDf3p2AV4tlM19iM2/fM8M5t3PKbvYAHSZx5uwGvFoMDvMYNvP2HGacIZ2TdoMHqMVAIpc4LfYzJM+k3fxDtBaeH4cTZ0iwH7tNlC2WzTyGM+c2PEuewZPDdlvGQIKHoF/M+c8YfHjz547tDPbjz26++WMjx9/eS8BhIIKxDUTygNk8eJXDtTD8ARHsDwiqHgWjYBSMgpEJAGhXSdSCGn09AAAAAElFTkSuQmCC","orcid":"","institution":"İzmir University of Economics Medical Point Hospital","correspondingAuthor":true,"prefix":"","firstName":"Pınar","middleName":"Tuğçe","lastName":"Özer","suffix":""},{"id":559277492,"identity":"79e6c8c1-4d46-4fac-ac6e-a084de5ec146","order_by":1,"name":"Kevser Arkan","email":"","orcid":"","institution":"Gazi Yaşargil Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kevser","middleName":"","lastName":"Arkan","suffix":""},{"id":559277493,"identity":"1ab7622d-bf2a-4ada-a542-cdfa72309751","order_by":2,"name":"Sedat Akgöl","email":"","orcid":"","institution":"Gazi Yaşargil Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Sedat","middleName":"","lastName":"Akgöl","suffix":""},{"id":559277495,"identity":"6ada5e23-378a-47c0-896f-f260adf00124","order_by":3,"name":"Sercan Kantarcı","email":"","orcid":"","institution":"İzmir Tepecik Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Sercan","middleName":"","lastName":"Kantarcı","suffix":""},{"id":559277497,"identity":"0f42c05e-b2b6-40fb-9927-9f53256a18dd","order_by":4,"name":"Adnan Budak","email":"","orcid":"","institution":"İzmir Tepecik Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Adnan","middleName":"","lastName":"Budak","suffix":""},{"id":559277499,"identity":"94b3b152-2100-43b5-9bc9-9b55efcb2b6d","order_by":5,"name":"Alper İleri","email":"","orcid":"","institution":"İzmir Tepecik Training and Research Hospital","correspondingAuthor":false,"prefix":"","firstName":"Alper","middleName":"","lastName":"İleri","suffix":""},{"id":559277500,"identity":"b8bf9ac3-c1e1-4b2c-b4c7-5b6b1e2d627f","order_by":6,"name":"Mehmet Özer","email":"","orcid":"","institution":"Erzurum City Hospital","correspondingAuthor":false,"prefix":"","firstName":"Mehmet","middleName":"","lastName":"Özer","suffix":""},{"id":559277501,"identity":"3db2e9e7-8d0b-4606-9b87-3d99d56c7b31","order_by":7,"name":"Meriç Balıkoğlu","email":"","orcid":"","institution":"İzmir University of Economics Medical Point 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08:58:06","extension":"html","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":145621,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/b8057c1925a891f8dd41a17d.html"},{"id":98432405,"identity":"f3971f47-75b3-4914-b9e6-924f9e668607","added_by":"auto","created_at":"2025-12-17 16:49:31","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":392697,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMarginal Effect Plot for ASFT\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003edisplays the marginal effect of ASFT on oxytocin dose, estimated while holding bishop score constant at its reference value, 0. The predicted values shown with the regression line suggest a positive association between ASFT and oxytocin dose, with higher ASFT values corresponding to increased predicted doses. The actual observations generally align with this trend, though some variability remains unexplained.\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/edd4af7d8679b04736f60ce2.png"},{"id":98207250,"identity":"93b3dc76-b2b1-4510-ade6-c28b834bf089","added_by":"auto","created_at":"2025-12-15 08:58:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":415073,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMarginal Effect of the Duration of Oxytocin Active Phase on Total Duration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003edisplays the marginal effect of the duration of oxytocin active phase on the total duration of labor, estimated while holding BMI, parity, oxytocin dose constant at their mean values and amniotomy at its reference value. The predicted values shown with the regression line suggest a positive association between the duration of oxytocin active phase and the total duration of labor, with higher the duration of oxytocin active phase values corresponding to increased predicted durations. The actual observations generally align with this trend, though some variability remains unexplained.\u003c/p\u003e","description":"","filename":"floatimage2.png","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/6e180774173d33bb758c9cd2.png"},{"id":98207247,"identity":"6834a11a-9e32-4b6d-8b88-2040d5fb234e","added_by":"auto","created_at":"2025-12-15 08:58:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":38222,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMarginal Effect BMI on Total Duration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003edisplays the marginal effect of BMI on the total duration of labor, estimated while holding the duration of oxytocin active phase, parity and oxytocin dose constant at their mean values and amniotomy at its reference value. The predicted values shown with the regression line suggest a positive association between BMI and the total duration of labor, with higher bmi values corresponding to increased predicted durations. The actual observations generally align with this trend, though some variability remains unexplained\u003c/p\u003e","description":"","filename":"floatimage3.png","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/8da0120bc9af4e7943d32748.png"},{"id":98207257,"identity":"1e1f0de0-4656-4b75-9ff8-2aba1497fbcc","added_by":"auto","created_at":"2025-12-15 08:58:06","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":349265,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003eMarginal Effect Oxytocin Dose on Total Duration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003edisplays the marginal effect of oxytocin dose on the total duration of labor, estimated while holding the duration of oxytocin active phase, bmi and parity constant at their mean values and amniotomy at its reference value. The predicted values shown with the regression line suggest a positive association between oxytocin dose and the total duration of labor, with higher oxytocin dose values corresponding to increased predicted durations. The actual observations generally align with this trend, though some variability remains unexplained\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/d609354e124379148ecfe33a.png"},{"id":98622230,"identity":"a852e54d-b0af-4e76-97ca-67b11e297f9a","added_by":"auto","created_at":"2025-12-19 16:49:32","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1856526,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/3cf92665-1777-491a-9b31-534a53429d54.pdf"},{"id":98207246,"identity":"f24a8cc3-db91-4f60-b028-1336c97a32c4","added_by":"auto","created_at":"2025-12-15 08:58:05","extension":"docx","order_by":1,"title":"","display":"","copyAsset":false,"role":"supplement","size":41337,"visible":true,"origin":"","legend":"","description":"","filename":"Tables.docx","url":"https://assets-eu.researchsquare.com/files/rs-8234858/v1/73cb70775d0c18d42ba28b2a.docx"}],"financialInterests":"No competing interests reported.","formattedTitle":"\u003cp\u003eComparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003eLabor induction is a common obstetric intervention to achieve vaginal delivery. Identifying and optimizing factors that influence its success can enhance the childbirth experience.\u003cbr\u003eHowever, predicting induction success remains challenging due to the heterogeneity and interplay of multiple maternal and fetal variables, making comparisons across studies difficult [1].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eObesity is among the key factors that may influence induction outcomes. In the United States, over 50% of women aged 20\u0026ndash;39 are overweight or obese, posing significant challenges for obstetric care. Although studies directly comparing induction methods in obese women are limited, existing data suggest that higher body mass index (BMI) is associated with reduced induction success.\u003cbr\u003eHowever, BMI alone may not accurately reflect body fat distribution. Abdominal subcutaneous fat thickness (ASFT) may affect metabolic pathways and, in turn, influence induction outcomes [2].\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTo contribute to the existing body of knowledge, this study aimed to compare body mass index (BMI) and abdominal subcutaneous fat thickness (ASFT) in predicting the success of labor induction. The findings may support the development of more effective induction strategies in obese pregnant women.\u003c/p\u003e"},{"header":"MATERIAL AND METHODS","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\u003ch2\u003eStudy Design and Participants\u003c/h2\u003e\u003cp\u003eThis prospective cohort study was carried out at Diyarbakır Gazi Yaşargil Training and Research Hospital, Turkey. Institutional ethical approval was obtained prior to data collection (Approval No: 2024/07\u0026ndash;23). The study included \u003cb\u003e193 term singleton pregnancies\u003c/b\u003e admitted for labor induction with oxytocin between 2024/06-2025/06. Informed consent was obtained from all individual participants included in the study.\u003c/p\u003e\u003cp\u003eWomen with multiple gestations, major fetal anomalies, elective cesarean section without labor attempt, or missing medical or ultrasonographic data were excluded from the analysis. Relevant maternal information\u0026mdash;such as age, gravidity, parity, pre-pregnancy body weight, gestational weight gain, height, BMI, and gestational age at admission\u0026mdash;was extracted from electronic health records.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eUltrasonographic Assessment of ASFT\u003c/h3\u003e\n\u003cp\u003eAt the time of hospital admission for delivery and prior to initiation of oxytocin infusion, abdominal subcutaneous fat thickness (ASFT) was assessed by a single trained obstetrician using transabdominal ultrasonography with a curvilinear probe (4\u0026ndash;8 MHz, GE Healthcare). All measurements were performed in accordance with standardized scanning protocols to ensure consistency.\u003c/p\u003e\u003cp\u003eThe measurement technique was based on a validated method previously described by P\u0026eacute;tursd\u0026oacute;ttir Maack et al [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. Scans were obtained in the longitudinal plane with careful attention to apply minimal probe pressure to avoid compression of the subcutaneous tissue.\u003c/p\u003e\u003cp\u003eDuring each assessment, the skin surface, linea alba, rectus abdominis muscle, umbilicus, and iliac crests were identified as anatomical landmarks to optimize visualization. ASFT was defined as the perpendicular distance from the outer skin surface to the anterior margin of the rectus abdominis muscle. The measurement point was standardized at the intersection of a horizontal line drawn between the most superior points of the bilateral iliac crests and the midline linea alba.\u003c/p\u003e\u003cp\u003eFor reliability, three independent measurements were obtained for each patient, and the mean value (in millimeters) was recorded. All ultrasonographic examinations were performed by the same operator, thereby minimizing inter-observer variability and enhancing reproducibility.\u003c/p\u003e\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\u003ch2\u003eStudy Outcomes\u003c/h2\u003e\u003cp\u003eThe primary outcome measures were:\u003c/p\u003e\u003cp\u003e\u003cb\u003eTotal cumulative oxytocin dose\u003c/b\u003e administered during the induction process (mU),\u003c/p\u003e\u003cp\u003e\u003cb\u003eMode of delivery\u003c/b\u003e following induction (vaginal vs. cesarean),\u003c/p\u003e\u003cp\u003e\u003cb\u003eLabor duration\u003c/b\u003e, specifically time intervals from the start of oxytocin to active labor and to delivery.\u003c/p\u003e\u003c/div\u003e\n\u003ch3\u003eData\u003c/h3\u003e\n\u003cp\u003eThe median age of participants was 27 years (IQR\u0026thinsp;=\u0026thinsp;9), with a height of 158 cm (IQR\u0026thinsp;=\u0026thinsp;8), weight of 72 kg (IQR\u0026thinsp;=\u0026thinsp;16), and BMI of 28.52 (IQR\u0026thinsp;=\u0026thinsp;5.58). Pre-pregnancy weight and BMI were 61.5 kg (IQR\u0026thinsp;=\u0026thinsp;14) and 24.22 (IQR\u0026thinsp;=\u0026thinsp;5.13), while gestational weight gain was 10 kg (IQR\u0026thinsp;=\u0026thinsp;5). Median abdominal subcutaneous fat thickness (ASFT) was 1.57 cm (IQR\u0026thinsp;=\u0026thinsp;0.79). Gravidity and parity were 3 (IQR\u0026thinsp;=\u0026thinsp;3) and 1 (IQR\u0026thinsp;=\u0026thinsp;3), respectively.\u003c/p\u003e\u003cp\u003eAt delivery, the median gestational age was 38.5 weeks (IQR\u0026thinsp;=\u0026thinsp;1.9). The oxytocin dose had a median of 5 units (IQR\u0026thinsp;=\u0026thinsp;5), with a maximum of 45 units (IQR\u0026thinsp;=\u0026thinsp;35). Induction lasted 130 minutes (IQR\u0026thinsp;=\u0026thinsp;168), the active phase 104 minutes (IQR\u0026thinsp;=\u0026thinsp;105), and the first and second labor stages 300 (IQR\u0026thinsp;=\u0026thinsp;165) and 20 minutes (IQR\u0026thinsp;=\u0026thinsp;22), respectively, for a total duration of 323 minutes (IQR\u0026thinsp;=\u0026thinsp;165). Median birth weight was 3,100 g (IQR\u0026thinsp;=\u0026thinsp;520), and Apgar scores were 8 and 9 at the 1st and 5th minutes.\u003c/p\u003e\u003cp\u003e Categorical data showed 69.43% of participants in Bishop Score group 2, 17.10% in group 1, and 13.47% in group 0. Amniotomy was performed in 52.85% of cases. BMI was classified into three groups (\u0026lt;\u0026thinsp;25, 25\u0026ndash;29.9, \u0026ge;\u0026thinsp;30), and ASFT into tertiles (\u0026le;\u0026thinsp;1.31, 1.32\u0026ndash;1.8, \u0026gt;\u0026thinsp;1.8). Bishop scores were dichotomized as \u0026lt;\u0026thinsp;6 (group 1) and \u0026ge;\u0026thinsp;6 (group 2).\u003c/p\u003e\u003cp\u003eThe study outcomes were oxytocin dose in relation to clinical variables and total labor duration, particularly its association with oxytocin use while adjusting for covariates.\u003c/p\u003e\n\u003ch3\u003eStatistical Methodology\u003c/h3\u003e\n\u003cp\u003eNormally distributed variables were compared using ANOVA with Tukey\u0026rsquo;s HSD or Games-Howell post-hoc tests, depending on variance homogeneity. Non-normally distributed variables were analyzed with the Kruskal-Wallis test, followed by Dunn\u0026rsquo;s pairwise comparisons. Significance was set at p\u0026thinsp;\u0026lt;\u0026thinsp;0.05.\u003c/p\u003e\u003cp\u003eFor regression, univariate, full multivariate, and stepwise models were applied to examine associations with labor duration, adjusting for demographic and clinical covariates. Marginal effects plots were generated to illustrate adjusted associations. Normality of continuous variables was assessed using the Shapiro\u0026ndash;Wilk test. Post-hoc pairwise comparisons were adjusted using Bonferroni correction to control for multiple testing.\u003c/p\u003e\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\u003ch2\u003eProgramming Environment\u003c/h2\u003e\u003cp\u003eAll of the steps carried out in the study were run in Python 3.12.1. The packages used in the analyses were numpy 1.26.3, pandas 2.0.3, statsmodels 0.14.2, scipy 1.12.0 and matplotlib 3.8.3.\u003c/p\u003e\u003c/div\u003e"},{"header":"RESULTS","content":"\u003cp\u003eWomen were stratified into three groups based on pre-pregnancy BMI, and their baseline characteristics and labor outcomes are summarized in Table\u0026nbsp;1. Maternal age and parity tended to be higher in the highest BMI category (Group 3) compared to the lowest (Group 1). In particular, Group 3 mothers were older on average (29.1 vs 24.9 years, p\u0026thinsp;=\u0026thinsp;0.003) and had a greater median parity (2 vs 1, p\u0026thinsp;=\u0026thinsp;0.032) than those in Group 1. As expected, pre-pregnancy weight and BMI differed significantly across the groups (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 for both), with Group 3 women weighing approximately 27 kg more than Group 1 on average at the start of pregnancy. Gestational weight gain was also higher in the obese group (median 12.0 kg in Group 3 vs 8.0 kg in Group 1, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). There were no significant differences in height or gestational age at delivery among the BMI groups (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). Newborn outcomes were similar across BMI categories: the 1-minute and 5-minute Apgar scores had medians of 8 and 9, respectively, in all groups. A slight difference in 5-minute Apgar reached nominal significance (p\u0026thinsp;=\u0026thinsp;0.049), though median values were identical (9 in each group). Importantly, neonatal birth weight increased with maternal BMI (median 3200 g in Group 3 vs 2950 g in Group 1, p\u0026thinsp;\u0026lt;\u0026thinsp;0.001).\u003c/p\u003e\u003cp\u003eLabor process measures showed notable variation by BMI category (Table\u0026nbsp;1). The duration of the first stage of labor was significantly prolonged in high-BMI women. Group 3 experienced a median first-stage labor of 416.5 minutes, compared to approximately 281 minutes in Groups 1 and 2 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 for Group 3 vs. both Group 1 and 2). Consistently, the total labor duration (from induction to delivery) was longest in Group 3 (median 452 minutes) and significantly greater than in the lower BMI groups (medians\u0026thinsp;~\u0026thinsp;300 minutes; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In contrast, the second stage of labor did not differ appreciably by BMI (median\u0026thinsp;~\u0026thinsp;20 minutes in all groups, p\u0026thinsp;=\u0026thinsp;0.800). Likewise, the induction-to-active labor interval and the total oxytocin dose required for induction were not significantly different among BMI groups (p\u0026thinsp;=\u0026thinsp;0.913 and p\u0026thinsp;=\u0026thinsp;0.985, respectively). Maximum oxytocin infusion rates and the duration of oxytocin administration in active labor were similar across the BMI categories (p\u0026thinsp;=\u0026thinsp;0.528 and p\u0026thinsp;=\u0026thinsp;0.349). The rate of amniotomy was also comparable (approximately 50% in each group, p\u0026thinsp;=\u0026thinsp;0.595). As an expected consequence of adiposity, Table\u0026nbsp;1 shows that women in the highest BMI group had significantly greater abdominal subcutaneous fat thickness (ASFT). The median ASFT in Group 3 was 1.92 cm versus 1.35 cm in Group 1 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and a majority (58.6%) of obese women fell into the highest ASFT category, compared to only 15.2% in the low-BMI group. Despite these differences, the distribution of Bishop score categories at induction was similar among BMI groups (p\u0026thinsp;=\u0026thinsp;0.380), indicating that initial cervical favorability did not differ by maternal BMI.\u003c/p\u003e\u003cp\u003eStratification by ASFT yielded similar trends (Table\u0026nbsp;2). Women with the greatest subcutaneous fat thickness (ASFT Group 3) tended to have higher BMI and weight, as the two measures were strongly correlated. Median BMI in ASFT Group 3 was 31.5, significantly higher than in Group 1 (26.8; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). ASFT Group 3 also had a higher proportion of obese patients (64% were BMI Group 3) compared to Group 1 (13.9%; p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Maternal height showed a small but significant difference across ASFT groups (p\u0026thinsp;=\u0026thinsp;0.017), with Group 2 being slightly taller on average than the others (median 161 cm vs 158 cm in Group 1). No significant differences were observed in maternal age, parity, or gravidity by ASFT category (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). In terms of labor outcomes, a higher ASFT was associated with a longer labor course. The median first-stage labor duration increased from 279 minutes in ASFT Group 1 to 372 minutes in Group 3 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Total labor time followed the same pattern, with Group 3 having the longest median duration (~\u0026thinsp;399.5 minutes) compared to ~\u0026thinsp;291 minutes in Group 1 (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Consequently, women in the highest ASFT category required more time to deliver after induction. However, other induction and delivery parameters were not significantly influenced by subcutaneous fat thickness. There were no differences among ASFT groups in second-stage duration, induction duration, or the need for oxytocin. The median total oxytocin dose was approximately 5\u0026ndash;6 units in all ASFT groups, and this did not vary significantly (p\u0026thinsp;=\u0026thinsp;0.713*). Similarly, the maximum oxytocin dose and the duration of oxytocin use in active labor were not significantly different, though the latter showed a trend toward increase with ASFT (median 120 minutes in Group 3 vs 90 minutes in Group 1, p\u0026thinsp;=\u0026thinsp;0.053). Newborn outcomes remained consistent: Apgar scores were uniformly high (median 8 and 9 at 1 and 5 minutes, respectively, p\u0026thinsp;\u0026gt;\u0026thinsp;0.90) regardless of maternal fat thickness, and median birth weight was slightly greater in the highest ASFT group (3200 g vs 3000 g in lowest, p\u0026thinsp;=\u0026thinsp;0.030).\u003c/p\u003e\u003cp\u003eWhen grouped by initial Bishop score (cervical favorability), most clinical characteristics and outcomes did not differ significantly (Table\u0026nbsp;3). Maternal BMI and ASFT showed no clear trend across Bishop score categories; for instance, median BMI ranged from ~\u0026thinsp;28 to 30 with p\u0026thinsp;=\u0026thinsp;0.353. An exception was observed in the intermediate Bishop category (Group 1), which had a higher median ASFT (1.89 cm) compared to the favorable Bishop group (1.50 cm in Group 2, p\u0026thinsp;=\u0026thinsp;0.010 for Group 1 vs 2). Gestational weight gain was also slightly higher in women with a Bishop score of 1 (median 12.0 kg) versus those with an unfavorable cervix (9.5 kg in Group 0, p\u0026thinsp;=\u0026thinsp;0.025). Despite these differences, parity and gravidity were similar across Bishop groups, as were maternal age and gestational age at delivery (all p\u0026thinsp;\u0026gt;\u0026thinsp;0.4). Labor progression metrics showed no major variation by Bishop score category in this cohort. Neither the first-stage nor total labor durations were significantly different among Bishop Groups 0, 1, and 2 (p\u0026thinsp;=\u0026thinsp;0.387 and p\u0026thinsp;=\u0026thinsp;0.412, respectively). Notably, however, the total amount of oxytocin required for induction was higher in women with a moderately favorable cervix (Bishop Group 1) compared to those with an unfavorable cervix. The median oxytocin dose in Group 1 was 10 units, versus 5 units in Group 0 (p\u0026thinsp;=\u0026thinsp;0.029*). Women with a favorable Bishop (Group 2) required a similar oxytocin amount as the unfavorable group (median 5 units), suggesting that the Group 1 patients paradoxically needed the most oxytocin. Rates of amniotomy were not significantly different between Bishop categories (p\u0026thinsp;=\u0026thinsp;0.052), although there was a trend toward fewer amniotomies in the lowest Bishop group. Newborn Apgar scores and birth weights did not vary with Bishop score, remaining consistent across groups (all medians 8/9 for Apgars, p\u0026thinsp;\u0026gt;\u0026thinsp;0.4; median birth weight\u0026thinsp;~\u0026thinsp;3100 g, p\u0026thinsp;=\u0026thinsp;0.939). These findings indicate that, aside from a slightly higher oxytocin requirement in the intermediate Bishop group, initial cervical readiness was not strongly associated with labor duration or other outcomes in our sample.\u003c/p\u003e\u003cp\u003eWe next examined predictors of oxytocin requirement using linear regression analyses (Tables\u0026nbsp;4 and 5). In univariate models, maternal abdominal fat thickness (ASFT) and Bishop score category showed significant relationships with the total oxytocin dose needed for induction. Each 1 cm increase in ASFT was associated with an estimated 1.73-unit increase in oxytocin consumption (p\u0026thinsp;=\u0026thinsp;0.001) in the unadjusted analysis. Likewise, having a Bishop score in Group 1 (moderately favorable) was linked to a higher oxytocin requirement, with women in this category needing approximately 2 units more oxytocin than those in Bishop Group 0 (p\u0026thinsp;=\u0026thinsp;0.013). In contrast, most other maternal factors \u0026mdash; including BMI, weight, age, parity, and gestational weight gain \u0026mdash; were not significantly associated with oxytocin dose on their own (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05). The total duration of labor showed a positive correlation with oxytocin dose in univariate analysis (p\u0026thinsp;=\u0026thinsp;0.006), and a higher maximum oxytocin infusion rate exhibited a trend toward significance (p\u0026thinsp;=\u0026thinsp;0.087), suggesting that more prolonged or intensive inductions tended to use larger oxytocin amounts.\u003c/p\u003e\u003cp\u003eMultivariate regression confirmed that ASFT and Bishop score were independent predictors of oxytocin requirement (Table\u0026nbsp;5). In the final stepwise model, only these two variables remained statistically significant. Controlling for other factors, each additional 1 cm of abdominal fat thickness was associated with a 1.59-unit increase in the oxytocin dose (p\u0026thinsp;=\u0026thinsp;0.002). Similarly, women with a Bishop score of 1 required on average 2.84 more oxytocin units than those with an unfavorable Bishop score (Group 0) (p\u0026thinsp;=\u0026thinsp;0.008). A favorable Bishop (Group 2) was not significantly different from Group 0 in oxytocin needs after adjustment. This model\u0026rsquo;s R\u0026sup2; was 0.09, indicating that about 9% of the variance in oxytocin dose was explained by maternal ASFT and Bishop score. Figure\u0026nbsp;1 illustrates the positive association between ASFT and oxytocin requirement. The marginal effect plot shows that higher maternal fat thickness corresponds to higher predicted oxytocin doses, with the regression line sloping upward. The observed data points generally align with this trend, although considerable individual variability is evident. Thus, while greater maternal subcutaneous fat and a mid-range Bishop score each contribute to higher oxytocin utilization, much of the variation in oxytocin requirement remains unexplained by these factors alone.\u003c/p\u003e\u003cp\u003eFinally, we analyzed factors associated with the total duration of labor. Table\u0026nbsp;6 presents univariate regression results for labor duration (measured from induction start to delivery). Several maternal characteristics and induction parameters showed significant unadjusted associations with how long labor lasted. Notably, indices of maternal adiposity were strong predictors: each 1 kg increase in maternal weight was associated with an approximately 3.14-minute longer labor (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), and each 1 unit increase in BMI corresponded to about 9.7 extra minutes of labor (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). Abdominal fat thickness had an even more pronounced effect size; an increase of 1 cm in ASFT was linked to an 81-minute prolongation of labor on average (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). In addition, greater oxytocin requirements signaled longer labors. For every 1 unit increase in total oxytocin dose, labor duration increased by about 6.8 minutes (p\u0026thinsp;=\u0026thinsp;0.006*). Likewise, each 1 mU/min higher in the maximum oxytocin infusion rate was associated with a 3.43-minute longer labor (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001). The length of the oxytocin-active phase of labor and the overall induction time were also strongly correlated with total labor duration: essentially, the longer a patient remained on oxytocin or waited for active labor, the longer the total time to delivery (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001 for both). On the other hand, obstetric history factors had the expected protective effect. Multiparous women labored for a significantly shorter time than primiparous women. Each additional prior birth was associated with about a 15-minute reduction in labor duration (p\u0026thinsp;=\u0026thinsp;0.010), and each increment in gravidity showed a similar trend (p\u0026thinsp;=\u0026thinsp;0.036). Variables such as maternal age, height, gestational age, and infant birth weight were not significant predictors of labor length in the univariate analysis (p\u0026thinsp;\u0026gt;\u0026thinsp;0.3). Performing an amniotomy was associated with a trend toward longer labor (+\u0026thinsp;38 minutes on average, p\u0026thinsp;=\u0026thinsp;0.066), but this did not reach statistical significance at the 0.05 level in univariate testing.\u003c/p\u003e\u003cp\u003eThe multivariable analysis identified five independent predictors of total labor duration (Table\u0026nbsp;7). In the final adjusted model (built via stepwise selection), the duration of oxytocin administration during active labor emerged as the strongest predictor of total labor time. Holding other factors constant, each additional minute of oxytocin use in active labor was associated with an increase of 0.80 minutes in the overall labor duration (p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001). Maternal BMI remained independently associated with labor length: for each 1-point increase in BMI, total labor was prolonged by about 11.5 minutes on average (p\u0026thinsp;\u0026lt;\u0026thinsp;0.001), after adjusting for other variables. Parity continued to have a significant inverse relationship with labor duration; each additional birth shortened the labor by roughly 14.6 minutes (p\u0026thinsp;=\u0026thinsp;0.002). The total amount of oxytocin administered also retained significance in the multivariate model \u0026ndash; even when accounting for the length of oxytocin use, a higher cumulative oxytocin dose predicted a longer labor (approximately\u0026thinsp;+\u0026thinsp;4.88 minutes per unit, p\u0026thinsp;=\u0026thinsp;0.008). Lastly, amniotomy was an independent factor: having an amniotomy performed was associated with an increase of about 38 minutes in total labor time compared to no amniotomy (p\u0026thinsp;=\u0026thinsp;0.013). Together, these five factors explained nearly half of the variability in labor duration (model R\u0026sup2; = 0.49, overall p\u0026thinsp;\u0026lt;\u0026thinsp;0.0001), indicating a moderate goodness-of-fit. The influence of key predictors on labor length is further illustrated in Figs.\u0026nbsp;2\u0026ndash;4. Figure\u0026nbsp;2 shows the marginal effect of the oxytocin active phase duration on total labor time, demonstrating a clear positive linear trend \u0026ndash; patients who required longer periods of oxytocin infusion experienced correspondingly longer labors. Similarly, Fig.\u0026nbsp;3 depicts a positive association between maternal BMI and labor duration when other factors are held constant; higher BMI values are linked with progressively longer induction-to-delivery intervals. Figure\u0026nbsp;4 highlights the relationship between total oxytocin dose and labor length, indicating that cases in which a larger amount of oxytocin was administered generally had prolonged labor courses. In all these plots, the observed data points align with the upward-sloping regression lines, though some degree of scatter is present. These findings underscore that greater maternal adiposity and higher oxytocin requirements are associated with longer induced labor, whereas multiparity tends to shorten it. Each significant predictor contributes to the duration of labor, and the multivariate model confirms that a combination of maternal factors and intervention-related factors jointly determine the length of induced labor in our cohort.\u003c/p\u003e"},{"header":"DISCUSSION","content":"\u003cp\u003eThis study investigated the effects of maternal BMI and anterior subcutaneous fat thickness (ASFT) on oxytocin requirements and total labor duration in term singleton pregnancies undergoing labor induction. Our findings suggest that both BMI and ASFT influence labor-related parameters, with ASFT appearing to be a more sensitive predictor of oxytocin need.\u003c/p\u003e\u003cp\u003eIn our study, patients with higher BMI and ASFT values had significantly longer total and first-stage labor durations, particularly in BMI\u0026thinsp;\u0026ge;\u0026thinsp;30 kg/m\u0026sup2; and ASFT\u0026thinsp;\u0026ge;\u0026thinsp;2.2 cm groups. These results align with previous findings suggesting that obesity may prolong both latent and active labor phases, contributing to dystocia. A large French cohort of over 7,500 term pregnancies also reported prolonged labor in nulliparous obese women (HR: 0.75; 95% CI: 0.64\u0026ndash;0.88), with no such association in multiparas, indicating potentially slower uterine contractility and cervical progression in obese nulliparas [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. A recent analysis involving over 35,000 births found shorter time to full cervical dilation in nulliparous women compared to the cohort reported by Zhang et al., which included more than 62,000 cases. The authors attributed this difference to a more homogeneous ethnic composition (94% White) and a lower mean pre-pregnancy BMI (21.8 vs. 23.4 kg/m\u0026sup2;) in their cohort. These findings indirectly support previous studies linking higher BMI with prolonged labor duration [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eEpidemiological data suggest that maternal adiposity influences the labor process not only through mechanical factors but also via biochemical mechanisms [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Carlson et al. (2020) showed that obesity-related metabolic pathways may impair uterine contractility via endocrine and inflammatory mechanisms. Lipid accumulation and altered myometrial signaling may contribute to labor dystocia in obese women [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eChen et al. (2020) found that pre-pregnancy overweight and obesity increased the risk of maternal and fetal complications, underscoring the need to address obesity before conception [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eAbdominal subcutaneous fat thickness (ASFT) has been associated not only with delivery outcomes but also with metabolic and inflammatory changes during pregnancy. In a study by Eley et al. (2020), second-trimester SCFT showed stronger associations with cesarean delivery, gestational diabetes, and hypertension than BMI. Other studies have also linked elevated SCFT with increased CRP and HbA1c levels, suggesting a potential role in systemic inflammation and metabolic stress that may indirectly influence labor [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn this study, ASFT was identified as a significant and independent predictor of oxytocin requirement, regardless of maternal BMI. Increasing ASFT values were associated with a linear rise in cumulative oxytocin dose. Additionally, evaluating ASFT alongside cervical parameters such as the Bishop score may enhance the prediction of oxytocin sensitivity and induction success.\u003c/p\u003e\u003cp\u003eSimilarly, a study by Carlson et al. in nulliparous women with spontaneous labor found a significant association between maternal BMI and oxytocin requirement, with BMI accounting for approximately 16.5% of the variance in hourly oxytocin dose. These findings suggest that while BMI may partially influence uterine contractility and oxytocin sensitivity, it may not fully reflect local soft tissue characteristics, such as those represented by ASFT [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e].\u003c/p\u003e\u003cp\u003eIn a prospective study by De Tina et al., oxytocin pharmacokinetics were evaluated in obese and non-obese pregnant women. While no significant differences were found in plasma oxytocin levels, the obese group had significantly lower plasma oxytocinase concentrations [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. This finding suggests that oxytocin metabolism may be influenced not only by circulating concentrations but also by tissue-level receptor responses and local enzymatic activity.\u003c/p\u003e\u003cp\u003eThe strong association observed in our study between ASFT and oxytocin requirement highlights the specific impact of local soft tissue thickness on uterine contractility\u0026mdash;beyond the commonly used BMI-based assessments. These findings support ASFT as a practical and feasible biometric parameter for predicting induction success.\u003c/p\u003e\u003cp\u003eDespite prolonged labor duration and increased oxytocin use in patients with elevated BMI and ASFT, neonatal outcomes did not differ significantly between groups. This suggests that appropriate clinical management strategies, including timely oxytocin adjustment and close fetal monitoring, may help preserve fetal outcomes. However, prolonged labor may increase the risk of maternal complications such as fatigue, infection or cesarean delivery [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. This study did not include maternal complications, which should be addressed in future research. Given the rising prevalence of obesity, incorporating maternal adipose tissue parameters into labor induction protocols may enhance clinical outcomes. Routine assessment of ASFT could support a more individualized approach to oxytocin management, particularly in high-risk populations.\u003c/p\u003e\u003cp\u003eThe strengths of our study include an adequate sample size, the inclusion of ASFT\u0026mdash;a relatively underexplored parameter\u0026mdash;and the use of regression analyses to evaluate potential confounders in detail. However, its prospective and single-center design, along with the exclusion of factors such as fetal position, contractility patterns, and provider variability, limit causal inferences. In addition, ASFT was measured only once before delivery, without accounting for its variation throughout pregnancy.\u003c/p\u003e\u003cp\u003eIn conclusion, both BMI and ASFT were associated with prolonged total labor duration; however, ASFT was also independently linked to increased oxytocin requirements. Incorporating ASFT into the antenatal assessment may improve labor management, particularly in populations with high obesity prevalence. Prospective, multicenter studies are needed to validate these findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors declare that no funds, grants, or other financial support were received during the preparation of this manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting Interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe authors have no relevant financial or non-financial interests to disclose.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor Contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll authors contributed to the study conception and design.\u003cbr\u003e\u0026nbsp;Material preparation, data collection, and analysis were performed by Pınar Tuğ\u0026ccedil;e \u0026Ouml;zer, Kevser Arkan, Sedat Akg\u0026ouml;l, Sercan Kantarcı, Adnan Budak, Alper İleri, Mehmet \u0026Ouml;zer, Meri\u0026ccedil; Balıkoğlu, Mesut Ali Halis\u0026ccedil;elik, and Şeyhmus Tun\u0026ccedil;.\u003cbr\u003e\u0026nbsp;The first draft of the manuscript was written by Pınar Tuğ\u0026ccedil;e \u0026Ouml;zer, and all authors commented on previous versions of the manuscript.\u003cbr\u003e\u0026nbsp;All authors read and approved the final manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eEthics Approval\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis study was designed as a prospective observational cohort study.\u003cbr\u003e\u0026nbsp;It was conducted in accordance with the principles of the Declaration of Helsinki.\u003cbr\u003e\u0026nbsp;Ethical approval was obtained from the Diyarbakır Gazi Yaşargil Training and Research Hospital Clinical Research Ethics Committee (Approval No: 2024/07-23).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Participate\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eInformed written consent was obtained from all individual participants included in the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent to Publish\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis manuscript contains no individual person\u0026rsquo;s data in any form (including images, identifiable details, or videos). Therefore, consent to publish is not applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical Trial Registration\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eClinical trial number: not applicable. Our study is a non-interventional observational cohort study and did not require clinical trial registration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of Data and Materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe datasets generated and analyzed during the current study are available from the corresponding author upon reasonable request.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eBatinelli L, Serafini A, Nante N, et al. Induction of labour: clinical predictive factors for success and failure. 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Eur J Obstet Gynecol Reproductive Biology. 2020;252:62\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003eTables are available in the Supplementary Files section.\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"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":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Abdominal subcutaneous fat thickness, Body mass index; Labor induction. Oxytocin-induced labor","lastPublishedDoi":"10.21203/rs.3.rs-8234858/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8234858/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003e\u003cstrong\u003ePurpose\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo compare body mass index (BMI) and abdominal subcutaneous fat thickness (ASFT) in predicting the success of oxytocin-induced labor and cumulative oxytocin requirement in term pregnancies.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMethods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eWe performed a prospective cohort study of 193 term singleton gravidas induced with oxytocin at a tertiary center in Turkey. ASFT was measured by standardized ultrasound before infusion. Primary outcomes were cumulative oxytocin dose and delivery mode; secondary outcomes included labor durations. Group comparisons used ANOVA/Kruskal–Wallis with post-hoc tests. Determinants of oxytocin dose and labor duration were analyzed by univariate and stepwise multivariable regression (p\u0026lt;0.05).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eResults\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eHigher BMI was associated with longer first-stage and total labor (both p\u0026lt;0.001), without a significant difference in oxytocin dose across BMI groups. Increasing ASFT tertiles were associated with longer first-stage and total labor (both p\u0026lt;0.001). In univariate analyses, ASFT (β=1.73, p=0.001) and Bishop score=1 vs 0 (β=1.98, p=0.013) predicted higher oxytocin dose. In multivariable models, ASFT (β=1.59, p=0.002) and Bishop score=1 (β=2.84, p=0.008) independently predicted oxytocin dose (R²=0.09). For total labor duration, the multivariable model identified active-phase duration (β=0.80, p\u0026lt;0.001), BMI (β=11.51, p\u0026lt;0.001), oxytocin dose (β=4.88, p=0.008), amniotomy (β=38.25, p=0.013), and parity (β=-14.56, p=0.002) as significant (R²=0.49). Neonatal Apgar scores were similar across groups.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConclusions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eBoth BMI and ASFT relate to prolonged labor, but ASFT is an independent predictor of cumulative oxytocin requirement, whereas BMI is not. Incorporating ASFT—alongside cervical status—may improve individualized induction planning, particularly in populations with high obesity prevalence. Prospective multicenter studies are warranted.\u003c/p\u003e","manuscriptTitle":"Comparison of the Effectiveness of Body Mass Index and Abdominal Subcutaneous Fat Thickness in Predicting the Success of Oxytocin-Induced Labor and Cumulative Oxytocin Requirement in Obese Pregnant Women","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-12-15 08:57:55","doi":"10.21203/rs.3.rs-8234858/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2026-04-13T15:53:23+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-05T11:30:28+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2026-02-01T14:08:04+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"251703028640549757473257106092914912547","date":"2026-01-28T07:19:31+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"191639068548020492577466391591903816149","date":"2026-01-27T11:27:01+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"165253596356474544283851427499084538132","date":"2026-01-25T22:43:17+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2025-12-10T07:31:57+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2025-12-01T18:51:55+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2025-11-30T23:05:39+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2025-11-30T23:05:32+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Pregnancy and Childbirth","date":"2025-11-29T06:27:57+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-pregnancy-and-childbirth","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"prch","sideBox":"Learn more about [BMC Pregnancy and Childbirth](http://bmcpregnancychildbirth.biomedcentral.com/)","snPcode":"","submissionUrl":"https://www.editorialmanager.com/prch/default.aspx","title":"BMC Pregnancy and Childbirth","twitterHandle":"@BMC_series","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"em","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"3924166c-8a68-4192-8f17-35fcac8ca5b3","owner":[],"postedDate":"December 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-05-02T11:39:58+00:00","versionOfRecord":[],"versionCreatedAt":"2025-12-15 08:57:55","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8234858","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8234858","identity":"rs-8234858","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}