Cumulative oxytocin dose during induction of labor according to maternal body mass index

A qualitative exploration of the challenges providers experience during peripartum management of patients with a body mass index ≥ 50 kg/m2 and recommendations for improvement

BACKGROUND

The objective of this research was to conduct a qualitative study among a diverse group of providers to identify their clinical needs, barriers, and adverse safety events in the peripartum care of people with a body mass index (BMI) ≥ 50 kg/m2.

METHODS

Obstetricians, anesthesiologists, certified nurse midwives, nurse practitioners, and nurses were invited to participate in focus group discussions if they were employed at the hospital for >6 months. Key concepts in the focus group guide included: (1) Discussion of challenging situations, (2) Current peripartum management approaches, (3) Patient and family knowledge and counseling, (4) Design and implementation of a guideline (e.g., checklist or toolkit) for peripartum care. The audiotaped focus groups were transcribed verbatim, uploaded to a qualitative analysis software program, and analyzed using inductive and constant comparative approaches. Emerging themes were summarized along with representative quotes.

RESULTS

Five focus groups of 27 providers were completed in 2023. The themes included staffing (level of experience, nursing-patient ratios, safety concerns), equipment (limitations of transfer mats, need for larger sizes, location for blood pressure cuff, patient embarrassment), titrating oxytocin (lack of guidelines, range of uses), monitoring fetal heart rate and contractions, patient positioning, and communication (lack of patient feedback, need for bias training, need for interdisciplinary relationships). Providers gave examples of items to include in a "BMI cart" and suggestions for a guideline including designated rooms for patients with a BMI ≥ 50 kg/m2, defining nursing ratios and oxytocin titration plans, postpartum incentive spirometer, and touch points with providers (nursing, physicians) at every shift change.

CONCLUSIONS

Providers discussed a range of challenges and described how current approaches to care may negatively affect the peripartum experience and pose threats to safety for patients with a BMI ≥ 50 kg/m2 and their providers. We gathered information on improving equipment and communication among providers.

Buccal Versus Vaginal Misoprostol Combined with a Foley Catheter among Individuals with Obesity Undergoing Induction

BACKGROUND

 Combining pharmacologic agents with mechanical ripening achieves the shortest labor duration, yet there is no clear evidence on route of drug administration in obese individuals. The use of buccal misoprostol has shown greater patient acceptance but remains understudied.

OBJECTIVE

 Our objective was to evaluate the difference in time to delivery of buccal compared with vaginal misoprostol in combination with a Foley catheter (FC) for induction of labor (IOL) in the obese population.

STUDY DESIGN

 This was a secondary analysis of a randomized controlled trial comparing identical dosages (25 μg) of buccal and vaginal misoprostol in combination with a FC. The parent trial was an institutional review board-approved, randomized clinical trial conducted from June 2019 through January 2020. Labor management was standardized among participants. Women undergoing IOL at ≥37 weeks with a singleton gestation and cervical dilation ≤2 cm were included. Body mass index (BMI, kg/m2) was stratified. The primary outcome was time to delivery.

RESULTS

 A total of 215 participants were included. Demographic characteristics were similar between the three groups. Vaginal drug administration achieved a faster median time to delivery than the buccal route among patients with a body mass index greater than or equal to 30 kg/m2 (vaginal misoprostol-FC: 21.3 hours vs. buccal misoprostol-FC: 25.2 hours, p = 0.006). There was no difference in the cesarean delivery rate between the two groups. Furthermore, patients with a BMI greater than or equal to 30 kg/m2 receiving vaginal misoprostol delivered 1.2 times faster than women who received buccal misoprostol after censoring for cesarean delivery and adjusting for parity (hazard ratio: 1.2, 95% confidence interval: 1.1-1.7). There were no significant differences in maternal and neonatal outcomes.

CONCLUSION

 We found that vaginal misoprostol was superior to buccal misoprostol when combined with a FC among individuals with a BMI greater than or equal to 30 kg/m2. Vaginal misoprostol should be the preferred route of drug administration for term IOL in this population.

KEY POINTS

· Vaginal misoprostol was superior to buccal route among patients with obesity.. · There was no difference in the cesarean delivery rate between the two groups.. · Vaginal misoprostol should be the preferred route of administration among patients with obesity..

Association between Maternal Serum Lipids and Intrapartum Oxytocin Requirements during Labor Induction and Augmentation

OBJECTIVE

 This study aimed to investigate the relationship between maternal serum lipid parameters and oxytocin requirements among women with term vaginal deliveries.

STUDY DESIGN

 In this secondary analysis of a prospective cohort study, women who presented for delivery at ≥37 weeks' gestation and received oxytocin during their labor were included. Maternal serum was collected intrapartum. The cohort was stratified into two groups based on maximum oxytocin infusion dose during labor. Primary outcomes were maternal total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), and triglyceride levels. Generalized linear regression models were used to assess the association between lipid parameters and maximum oxytocin dose requirements while controlling for potential confounders. For secondary analyses, the cohort was stratified by HDL-C into two groups. Multivariable logistic regression was used to evaluate the relationship between low maternal HDL-C and additional intrapartum oxytocin parameters.

RESULTS

 There were no differences in maternal total cholesterol, LDL-C, or triglyceride values between high and low maximum oxytocin groups. Median serum HDL-C was significantly lower among women in the high oxytocin group compared with those in the low oxytocin group (56 vs. 62 mg/dL, p < 0.01). For every 0.26 mg/dL lower HDL-C, women had 1 mU/min higher maximum oxytocin infusion dose during labor. Women with low serum HDL-C were also more likely to require maximum oxytocin doses above the 75th percentile (adjusted odds ratio [aOR]: 1.99, 95% confidence interval [CI]: 1.06-3.75) and above the 90th percentile (aOR: 2.47, 95% CI: 1.10-5.54). Among women undergoing induction of labor, low serum HDL-C was also associated with longer duration of oxytocin infusion (aOR: 2.07, 95% CI: 1.02-4.20).

CONCLUSION

 Low maternal HDL-C levels at term are associated with higher maximum oxytocin infusion doses among women undergoing labor induction or augmentation. Given the growing prevalence of metabolic syndrome in the United States and persistently high rates of cesarean delivery, HDL-C or its components may present a new target for predicting and improving labor outcomes.

KEY POINTS

· Serum HDL-C at term is inversely correlated with oxytocin infusion doses at term.. · Low maternal serum HDL-C is associated with higher oxytocin requirements during labor induction or augmentation.. · No association between maternal serum total cholesterol, LDL-C, or triglyceride levels and oxytocin requirements in labor..

Cumulative oxytocin dose in spontaneous labour - Adverse postpartum outcomes, childbirth experience, and breastfeeding

OBJECTIVES

This study aimed to determine the association between the total cumulative oxytocin dose during labour and adverse postpartum outcomes, childbirth experience and breastfeeding in term primiparous women with spontaneous onset of labour.

STUDY DESIGN

A prospective observational multicentre study, including 1395 women with spontaneous labour, in seven hospitals in Southeast Sweden. Multivariable logistic regression (Crude Odds Ratios (OR) and adjusted OR (aOR) for relevant confounders) was used to analyze the association between oxytocin dose and postpartum outcomes. The exposure was the cumulative oxytocin dose during labour, classified in percentiles (<25th, 25-75th, >75th). The outcomes were occurrence of obstetric anal sphincter injury, postpartum haemorrhage (blood loss > 1000 ml), Apgar score < 7 at five minutes, umbilical cord arterial pH, postpartum bladder overdistension, exclusive breastfeeding at one week and three months, and the woman's perceived birth experience.

RESULTS

Women receiving high amounts (>75th percentile, >4370 mU) of oxytocin infusion during labour had an increased risk of postpartum haemorrhage (OR 2.73 (1.78-4.19)), an overdistended bladder (OR 2.19 (1.11-4.31)), an infant with an Apgar score < 7 at five minutes (OR 2.89 (1.27-6.57)), a negative birth experience (OR 1.83 (1.25-2.69)), and a decreased chance of exclusive breastfeeding at one week (OR 0.63 (0.41-0.96)). After adjusting for confounders, all outcomes remained statistically significant except risk of low Apgar score and chance of exclusive breastfeeding.

CONCLUSION

In women with high cumulative oxytocin dose during labour prompt, and prophylactic administration of uterotonics after delivery of the placenta should be considered to reduce the risk of postpartum haemorrhage. The risk for bladder overdistension can be reduced by implementing routines for observation for signs of bladder filling in the early postpartum period, as well as routine use of bladder scans post micturition to assess for successful bladder emptying. As women's birth experience have a major impact on their future mental health, should be routinely assessed postpartum, and support should be offered to women with negative experiences.

Feasibility Study to Compare Oxytocin Function Between Body Mass Index Groups at Term Labor Induction

OBJECTIVE

To determine the feasibility of a protocol to examine the association between oxytocin system function and birth outcomes in women with and without obesity before induction of labor.

DESIGN

Prospective descriptive.

SETTING

Academic medical center in the U.S. Midwest.

PARTICIPANTS

Pregnant women scheduled for induction of labor at 40 weeks of gestation or greater (n = 15 normal weight; n = 15 obese).

METHODS

We collected blood samples and abstracted data by chart review. We used percentages to examine adherence to protocol. We used t tests and chi-square tests to describe differences in sample characteristics, oxytocin system function variables, and birth outcomes between the body mass index groups.

RESULTS

The recruitment rate was 85.7%, protocol adherence was 97.1%, and questionnaire completion was 80.0%. Mean plasma oxytocin concentration was higher in the obese group (M = 2774.4 pg/ml, SD = 797.4) than in the normal weight group (M = 2193.5 pg/ml, SD = 469.8). Oxytocin receptor DNA percentage methylation (CpG -934) was higher in the obese group than in the normal weight group.

CONCLUSION

Our protocol was feasible and can serve as a foundation for estimating sample sizes in forthcoming studies investigating the diversity in oxytocin system measurements and childbirth outcomes among pregnant women in different body mass index categories.

Weight-based versus fixed dose oxytocin infusion for preventing uterine atony during cesarean section in laboring patients: A randomized trial

OBJECTIVE

We compared efficacy of weight-based (0.4 IU/kg/h) versus fixed-dose (34 IU/h) oxytocin infusion during cesarean section.

METHODS

The oxytocin infusion in either group (n = 32 each) was initiated upon cord clamping. Primary outcome measure was adequacy of uterine tone at 4 min after initiating oxytocin infusion. Oxytocin associated side effects were also observed.

RESULTS

Significantly less oxytocin was used with the weight-based versus fixed-dose regimen (16.3 [11.2-22.4] IU vs 20.4 [15.8-26.9] IU; P = 0.036). Incidence of adequate uterine tone was clinically greater but not significantly different with the weight-based versus fixed-dose regimen (81.3% vs 71.9%; P = 0.376). The weight-based regimen was associated with clinically lesser, although not statistically significant need for rescue oxytocin (25% vs 46.9%; P = 0.068) and additional uterotonic (9.4% vs 15.6%; P = 0.708); as well as oxytocin associated side effects (hypotension [34.4% vs 46.9%; P = 0.309], nausea/vomiting [18.8% vs 40.6%; P = 0.055], and ST-T changes [0% vs 3.1%; P = 1.000]).

CONCLUSION

Weight-based oxytocin was not significantly different from the fixed-dose regimen in terms of uterotonic efficacy or associated side-effects, despite significantly lower doses being used. Use of weight-based oxytocin infusion (0.4 IU/kg/h) can be considered in clinical practice.

TRIAL REGISTRATION

Clinical Trial Registry of India (ctri.nic.in, number. CTRI/2021/01/030642).

Maternal oxytocin treatment at birth increases epigenetic age in male offspring

Exogenous oxytocin (OT) is widely used to induce or augment labor with little understanding of the impact on offspring development. In rodent models, including the prairie vole (Microtus ochrogaster), it has been shown that oxytocin administered to mothers can affect the nervous system of the offspring with long lasting behavioral effects especially on sociality. Here, we examined the hypothesis that perinatal oxytocin exposure could have epigenetic and transcriptomic consequences. Prairie voles were exposed to exogenous oxytocin, through injections given to the mother just prior to birth, and were studied at the time of weaning. The outcome of this study revealed increased epigenetic age in oxytocin-exposed animals compared to the saline-exposed group. Oxytocin exposure led to 900 differentially methylated CpG sites (annotated to 589 genes), and 2 CpG sites (2 genes) remained significantly different after correction for multiple comparisons. Differentially methylated CpG sites were enriched in genes known to be involved in regulation of gene expression and neurodevelopment. Using RNA-sequencing we also found 217 nominally differentially expressed genes (p<0.05) in nucleus accumbens, a brain region involved in reward circuitry and social behavior; after corrections for multiple comparisons 6 genes remained significantly differentially expressed. Finally, we found that maternal oxytocin administration led to widespread alternative splicing in the nucleus accumbens. These results indicate that oxytocin exposure during birth may have long lasting epigenetic consequences. A need for further investigation of how oxytocin administration impacts development and behavior throughout the lifespan is supported by these outcomes.

The minimum effective dose (ED90) of prophylactic oxytocin infusion during cesarean delivery in patients with and without obesity: an up-down sequential allocation dose-response study

BACKGROUND

Obesity is associated with greater oxytocin requirement during labor induction or augmentation. There are scant data exploring the intra-operative requirement during cesarean delivery in patients with obesity, and none comparing it with those without obesity. We evaluated the minimum effective dose (ED90) of an oxytocin infusion to achieve adequate uterine tone during cesarean delivery in patients with and without obesity.

METHODS

Patients (body mass index ≥30 kg/m2 represented patients with obesity) undergoing cesarean delivery using subarachnoid block were included. This prospective dual-arm dose-finding study used a 9:1 biased sequential allocation design. Oxytocin infusion was initiated at 13 IU/h at cord clamping in the first patient of each group. Uterine tone was graded as satisfactory or unsatisfactory by the obstetrician four minutes after initiation of the infusion. The dose of oxytocin infusion for subsequent patients was determined according to the response of the previous patient in the group. Oxytocin-associated side effects were evaluated. Dose-response data for the groups was evaluated using log-logistic function and ED90 estimates derived from fitted equations using the delta method.

RESULTS

The ED90 of oxytocin was significantly higher for patients with obesity (n = 40) compared with those without obesity (n = 40) [25.7 IU/h, 95% CI 18.6 to 32.9) vs. 16.6 IU/h, 95% CI 14.9 to 18.3)]; relative ratio 1.55 [95% CI 1.09 to 2.01] (P = 0.019).

CONCLUSIONS

Patients with obesity require a higher intra-operative oxytocin infusion dose rate to achieve a satisfactorily contracted uterus after fetal delivery when compared with patients without obesity.

Evidence Based Management of Labor

Importance

Induction of labor (IOL) is a common obstetric intervention. Augmentation of labor and active management of the second stage is frequently required in obstetric practice. However, techniques around labor and induction management vary widely. Evidence-based practice regarding induction and labor management can reduce birth complications such as infection and hemorrhage and decrease rates of cesarean delivery.

Objective

To review existing evidence on IOL and labor management strategies with respect to preparing for induction, cervical ripening, induction and augmentation, and second stage of labor techniques.

Evidence acquisition

Review of recent original research, review articles, and guidelines on IOL using PubMed (2000-2022).

Results

Preinduction, pelvic floor training and perineal massage reduce postpartum urinary incontinence and perineal trauma, respectively. Timely membrane sweeping (38 weeks) can promote spontaneous labor and prevent postterm inductions. Outpatient Foley bulb placement in low-risk nulliparous patients with planned IOL reduces time to delivery. Inpatient Foley bulb use beyond 6 to 12 hours shows no benefit. When synthetic prostaglandins are indicated, vaginal misoprostol should be preferred. For nulliparous patients and those with obesity, oxytocin should be titrated using a high-dose protocol. Once cervical dilation is complete, pushing should begin immediately. Warm compresses and perineal massage decrease risk of perineal trauma.

Conclusion and relevance

Several strategies exist to assist in successful IOL and promote vaginal delivery. Evidence-based strategies should be used to improve outcomes and decrease risk of complications and cesarean delivery. Recommendations should be shared across interdisciplinary team members, creating a model that promotes safe patient care.

Association of maternal Body Mass Index and parity on induced labor stages

BACKGROUND

Obesity is a widespread pandemic and obstetric care must adapt to meet the needs of obese pregnant women. Little is known about the impact of Body Mass Index (BMI) on the induction of labor (IOL). Therefore, our objective was to evaluate if the duration of the first and second stages of IOL is affected by maternal BMI in nulliparous and multiparous women.

METHODS

We included singleton pregnancies at term with cephalic presentation whose labor was induced from June 2018 to December 2019. Women were divided into two groups according to pre-pregnancy BMI in normal weight and obese women.

RESULTS

A total of 668 women with IOL were included in the study, among them, 349 had a normal weight and 321 were obese. The first stage of labor was longer in obese multiparous than normal-weight women (normal weight 81.98±71.7 vs. obese 134.3±158.1 min, P=0.000), while the second stage resulted significantly shorter (normal weight 22.2±27.8 vs. obese 14.3±14.2 min, P=0.000). The total time elapsed from IOL beginning and delivery was significantly higher in obese nulliparous (normal weight 10.4±19.7 vs. obese 22.0±26.2 h, P=0.000). Operative vaginal deliveries, emergency cesarean section, and failed IOL resulted to be similar between the groups.

CONCLUSIONS

Obese multiparous women have longer first stages of labor while shorter second stages. The total time for induced obese nulliparous to reach delivery is higher than the normal weight. It might be reasonable to reconsider the partographs according to maternal BMI in case of induced labor for future obstetric practice.

Ubhayasekera K, Kjölhede P, Bergquist J, Blomberg M. The association between maternal body mass index and serial plasma oxytocin levels during labor

OBJECTIVE

To evaluate the association between maternal body mass index (BMI) and plasma oxytocin (OT) levels at different OT infusion rates in labor.

METHODS

A prospective observational study analyzing serial plasma samples in laboring women with OT infusion. The women were categorized into three groups, women with non-obesity (BMI 18.5-29.9, n = 12), obesity (BMI 30.0-34.9, n = 13), and morbid obesity (BMI ≥ 35.0, n = 15). Plasma OT was analyzed using tandem mass spectrometry.

RESULTS

Except for a low positive correlation between OT levels and BMI and significantly increased plasma OT levels in women with morbid obesity at the OT infusion rate of 3.3 mU/min, no significant differences in OT levels between the BMI groups were found. Further, the inter-individual differences in OT levels were large and no dose-dependent increase of OT levels was seen.

CONCLUSIONS

Other factors than plasma OT levels may be more likely to determine the clinical response of OT infusion in women with obesity. Perhaps the observed clinical need and individual response would be a better predictor of plasma OT levels than a pre-determined OT infusion rate. The OT dosage guidelines for labor augmentation should be individualized according to clinical response rather than generalized.

TRIAL REGISTRATION

Clinical trial registration: ClinicalTrials.gov ID NCT04093479.

The Relationship Between Uterine Activity, Oxytocin Dosing, Labor Progress, and Mode of Birth in Nulliparas with Obesity: Minimal Usefulness of Montevideo Unit Measurement

BACKGROUND

Maternal obesity and cesarean birth disproportionately affect Black parturients; thus, prevention of cesarean birth is a key modifiable factor to improve pregnancy outcomes and reduce disparities. The primary driver of unplanned cesarean birth among people with higher body mass index is prolonged labor duration. However, strategies to optimize outcomes in these situations have not been established. We aimed to evaluate the influence of oxytocin augmentation on uterine activity and labor progression in nulliparas with obesity.

METHODS

This secondary analysis involved nulliparas with obesity (BMI ≥30 kg/m2) who had spontaneous labor onset followed by oxytocin augmentation and an intrauterine pressure catheter. Using Linear Mixed Models, we evaluated relationships between uterine activity measured in Montevideo units (MVU), oxytocin dose, and rate of cervical dilation normalized by labor duration.

RESULTS

In this diverse sample (35.6% Caucasian, 16.11% African American, 40.2% Hispanic) of nulliparas with obesity (n = 87; BMI 35.54 ± 4.38 kg/m2), 31% ended labor with cesarean birth. Among those with vaginal birth, only 13% had MVU ≥200 prior to the final 2 hours of labor. MVUs were only minimally responsive to oxytocin dose and were not associated with labor progression nor birth route.

CONCLUSION

MVU measurements may not be useful to diagnose labor arrest in nulliparas with obesity. Optimizing care for birthing people with obesity is essential for improving perinatal outcomes and for reducing racial health disparities.

Disparities by race/ethnicity in unplanned cesarean birth among healthy nulliparas: a secondary analysis of the nuMoM2b dataset

BACKGROUND

Racial disparities exist in maternal morbidity and mortality, with most of these events occurring in healthy pregnant people. A known driver of these outcomes is unplanned cesarean birth. Less understood is to what extent maternal presenting race/ethnicity is associated with unplanned cesarean birth in healthy laboring people, and if there are differences by race/ethnicity in intrapartum decision-making prior to cesarean birth.

METHODS

This secondary analysis of the Nulliparous Pregnancy Outcomes Study: Monitoring Mothers-to-Be (nuMoM2b) dataset involved nulliparas with no significant health complications at pregnancy onset who had a trial of labor at ≥ 37 weeks with a singleton, non-anomalous fetus in cephalic presentation (N = 5,095). Logistic regression models were used to examine associations between participant-identified presenting race/ethnicity and unplanned cesarean birth. Participant-identified presenting race/ethnicity was used to capture the influence of racism on participant's healthcare experiences.

RESULTS

Unplanned cesarean birth occurred in 19.6% of labors. Rates were significantly higher among Black- (24.1%) and Hispanic- (24.7%) compared to white-presenting participants (17.4%). In adjusted models, white participants had 0.57 (97.5% CI [0.45-0.73], p < 0.001) lower odds of unplanned cesarean birth compared to Black-presenting participants, while Hispanic-presenting had similar odds as Black-presenting people. The primary indication for cesarean birth among Black- and Hispanic- compared to white-presenting people was non-reassuring fetal heart rate in the setting of spontaneous labor onset.

CONCLUSIONS

Among healthy nulliparas with a trial of labor, white-presenting compared to Black or Hispanic-presenting race/ethnicity was associated with decreased odds of unplanned cesarean birth, even after adjustment for pertinent clinical factors. Future research and interventions should consider how healthcare providers' perception of maternal race/ethnicity may bias care decisions, leading to increased use of surgical birth in low-risk laboring people and racial disparities in birth outcomes.

Oxytocin receptor DNA methylation is associated with exogenous oxytocin needs during parturition and postpartum hemorrhage

BACKGROUND

The oxytocin receptor gene (OXTR) is regulated, in part, by DNA methylation. This mechanism has implications for uterine contractility during labor and for prevention or treatment of postpartum hemorrhage, an important contributor to global maternal morbidity and mortality.

METHODS

We measured and compared the level of OXTR DNA methylation between matched blood and uterine myometrium to evaluate blood as an indicator of uterine methylation status using targeted pyrosequencing and sites from the Illumina EPIC Array. Next, we tested for OXTR DNA methylation differences in blood between individuals who experienced a postpartum hemorrhage arising from uterine atony and matched controls following vaginal birth. Bivariate statistical tests, generalized linear modeling and Poisson regression were used in the analyses.

RESULTS

Here we show a significant positive correlation between blood and uterine DNA methylation levels at several OXTR loci. Females with higher OXTR DNA methylation in blood had required significantly more exogenous oxytocin during parturition. With higher DNA methylation, those who had oxytocin administered during labor had significantly greater relative risk for postpartum hemorrhage (IRR 2.95, 95% CI 1.53-5.71).

CONCLUSIONS

We provide evidence that epigenetic variability in OXTR is associated with the amount of oxytocin administered during parturition and moderates subsequent postpartum hemorrhage. Methylation can be measured using a peripheral tissue, suggesting potential use in identifying individuals susceptible to postpartum hemorrhage. Future studies are needed to quantify myometrial gene expression in connection with OXTR methylation.

High- vs low-dose oxytocin in lean and obese women: a double-blinded randomized controlled trial

BACKGROUND

Women with obesity are likely to experience longer lengths of labor and are at an increased risk of cesarean delivery. We hypothesized that high-dose oxytocin would decrease the time to delivery in a cohort of women with obesity undergoing induction of labor.

OBJECTIVE

This study aimed to assess whether women with obesity benefited from higher doses of oxytocin for induction of labor.

STUDY DESIGN

A double-blinded randomized controlled trial was conducted to evaluate the effect of low-dose and high-dose oxytocin on length of labor. We recruited women who were undergoing induction of labor at ≥37 weeks of gestation. Patients were randomly assigned in a 1:1 ratio to receive low-dose or high-dose oxytocin stratified by obesity level (obese and lean). The primary outcome was length of time (minutes) to vaginal delivery. The secondary outcomes included overall cesarean delivery rate, cesarean delivery for labor arrest, maximum oxytocin infusion rate, oxytocin infusion discontinuation, oxytocin infusion decrease, blood loss, neonatal intensive care unit admission, and neonatal Apgar scores.

RESULTS

A total of 140 patients were randomized into receiving low-dose and high-dose oxytocin stratified into obese and lean stratum (35 for all strata). The primary outcome, time to vaginal delivery, was similar between the low-dose and high-dose oxytocin groups in the lean stratum (796 [±411] vs 694 [±466] minutes; P=.363) and the stratum with obesity (715 [±497] vs 762 [±594] minutes; P=.733). Kaplan-Meier curves between the low-dose and high-dose oxytocin groups were not significantly different in the lean stratum (P=.391) and the stratum with obesity (P=.692). There were 5 cesarean deliveries (14.29%) in the low-dose oxytocin lean stratum vs 2 cesarean deliveries (5.71%) in the high-dose oxytocin lean stratum (P=.232). There were 4 cesarean deliveries (11.43%) in the low-dose oxytocin stratum with obesity vs 1 cesarean delivery (2.86%) in the high-dose oxytocin stratum with obesity (P=.164). There was no difference in the incidence of postpartum hemorrhage between the lean stratum (P=0.526) and the stratum with obesity (P=0.212). There was no difference in mean estimated blood loss between the lean stratum (P=.472) and the stratum with obesity (P=.215).

CONCLUSION

There was no difference in time to delivery between the low-dose and high-dose oxytocin protocols in either the lean cohorts or cohorts with obesity undergoing induction of labor. We did observe a trend toward a lower rate of cesarean delivery in both lean women and women with obesity when high-dose oxytocin was used.

Labor induction with oxytocin in pregnant rats is not associated with oxidative stress in the fetal brain

Despite the widespread use of oxytocin for induction of labor, mechanistic insights into fetal/neonatal wellbeing are lacking because of the absence of an animal model that recapitulates modern obstetric practice. Here, we create and validate a hi-fidelity pregnant rat model that mirrors labor induction with oxytocin in laboring women. The model consists of an implantable preprogrammed microprocessor-controlled infusion pump that delivers a gradually escalating dose of intravenous oxytocin to induce birth at term gestation. We validated the model with molecular biological experiments on the uterine myometrium and telemetry-supported assessment of changes in intrauterine pressure. Finally, we applied this model to test the hypothesis that labor induction with oxytocin would be associated with oxidative stress in the newborn brain. Analysis of biomarkers of oxidative stress and changes in the expression of associated genes were no different between oxytocin-exposed and saline-treated pups, suggesting that oxytocin-induced labor was not associated with oxidative stress in the developing brain. Collectively, we provide a viable and realistic animal model for labor induction and augmentation with oxytocin that would enable new lines of investigation related to the impact of perinatal oxytocin exposure on the mother-infant dyad.

Induction of labour in pregnant individuals with obesity

People with obesity may require induction of labour (IoL) due to a higher incidence of pre-existing comorbidities and pregnancy complications, as well as to prevent post-term pregnancies and late-term stillbirths. IoL at 39-40 weeks is associated with fewer caesarean births and lower morbidity for the pregnant person and neonate when compared with expectant management. Ensuring the success and safety of IoL in people with obesity requires adherence to evidence-based protocols for the management of labour induction and augmentation. Cervical ripening as well as the latent and active phases of labour in people with obesity may be considerably prolonged, requiring higher cumulative doses of oxytocin. This should be guided by intrauterine pressure catheters and early provision of neuraxial analgesia, where possible. There is insufficient evidence to recommend one method of IoL over another. The need for higher doses of prostaglandins and concurrent agents for cervical ripening should be studied in prospective studies.

Risk of Cesarean Delivery for Women with Obesity Using a Standardized Labor Induction Protocol

OBJECTIVE

We aimed to determine the risk of cesarean among women with obesity undergoing labor induction within a prospective trial that utilized a standardized labor protocol.

STUDY DESIGN

This was a secondary analysis of a randomized trial of induction methods. Term (≥37 weeks) women with intact membranes undergoing induction with an unfavorable cervix (Bishop's score ≤6 and dilation ≤2 cm) were included. The trial utilized a labor protocol that standardized induction and active labor management, with recommendations for interventions at particular time points. Only women with a recorded body mass index (BMI) at prenatal care start were included in this analysis. The primary outcome was cesarean delivery compared between obese (≥30 kg/m²) and nonobese (<30 kg/m²) women. Indication for cesarean was also evaluated.

RESULTS

A total of 465 women were included: 207 (44.5%) obese and 258 (55.5%) nonobese. Women with obesity had a higher risk of cesarean compared with women without obesity (33.3 vs. 23.3%, p = 0.02), even when adjusting for parity, weight change over pregnancy, and indication for induction (adjusted relative risk [aRR] = 1.79, 95% confidence interval [CI]: [1.34-2.39]). Compared with women without obesity, women with obesity had a higher risk of failed induction (47.8 vs. 26.7%, p = 0.01) without a difference in arrest of active phase (p = 0.39), arrest of descent (p = 0.95) or fetal indication (p = 0.32), despite adherence to a standardized labor protocol.

CONCLUSION

Compared with women without obesity, women with obesity undergoing an induction are at increased risk of cesarean, in particular a failed induction, even within the context of standardized induction management. As standardized practices limit provider variation in labor management, this study may support physiologic differences in labor processes secondary to obesity.

KEY POINTS

· Even with a standardized induction protocol, women with obesity are at higher risk of cesarean.. · In particular, women with obesity are at increased risk of cesarean for failed induction.. · These findings support a possible biologic relationship between obesity and failed induction..

Oxytocin administration for induction and augmentation of labour in polish maternity units - an observational study

BACKGROUND

There is not enough data regarding practices and protocols on the dose of oxytocin administrated to women during labour. Empirical evidence indicates that compliance with the guidelines improves the quality of healthcare and reduces adverse effects. The study aimed to evaluate practices of oxytocin provision for labour induction and augmentation in two maternity units in Poland.

METHODS

The article presents a prospective observational study. Data from 545 (n = 545) labours was collected in two maternity units. First, the total dose (the total amount of oxytocin provided from the beginning in the labour ward until delivery including the III and IV stage of labour) and cumulative dose of oxytocin (the amount of oxytocin given until the birth of the neonate) administered to women during labour was calculated. Then, the relationship between the cumulative dose of oxytocin and short term perinatal outcomes (mode of delivery, use of epidural anaesthesia, Apgar scores, birth weight and postpartum blood loss) was analysed. Finally, the compliance of oxytocin supply during labour with national guidelines in the following five criteria: medium, start dose, escalation rate, interval, the continuation of infusion after established labour was examined.

RESULTS

The average cumulative dose of oxytocin administrated to women before birth was 4402 mU following labour induction and 2366 mU following labour augmentation. The actual administration of oxytocin deviated both from the unit and national guidelines in 93.6% of all observed labours (mainly because of continuation of infusion after established labour). We found no statistically significant correlation between the cumulative dose of oxytocin administered and mode of delivery, immediate postpartum blood loss or Apgar scores. There was no observed effect of cumulative dose oxytocin on short-term perinatal outcomes. The two units participating in the study had similar protocols and did not differ significantly in terms of total oxytocin dose, rates of induction and augmentation - the only observed difference was the mode of delivery.

CONCLUSIONS

The study showed no effect of the mean cumulative oxytocin dose on short-term perinatal outcomes and high rate of non-compliance of the practice of oxytocin administration for labour induction and augmentation with the national recommendations. Cooperation between different professional groups of maternity care providers should be considered in building national guidelines for maternity care.. Further studies investigating possible long-term effects of the meant cumulative dose of oxytocin and the reasons for non-compliance of practice with guidelines should be carried out.

Predicting factors of failed induction of labor in three hospitals of Southwest Ethiopia: a cross-sectional study

Introduction

Failed induction of labor affects maternal and neonatal outcomes as well as the cost of healthcare, especially in low-resource setting regions in which the prevalence of failed induction is higher despite the incidence of labor induction is low. This study aimed to assess the prevalence of failed induction of labor in southwest Ethiopia.

Method

A hospital-based cross-sectional study was conducted among 441 induced women from March 1 to August 30, 2018. A systematic random sampling technique was used to select study participants. Data were collected using a pretested and structured questionnaire. Bivariable and multivariable logistic regression models were done and fitted to identify predictors of failed induction. An adjusted odds ratio with 95% confidence interval (CI) was calculated to determine the level of significance.

Result

Premature rupture of membrane was the most common cause of labor induction and the commonly used method of labor induction were oxytocin infusion. Cesarean section was done for 28.1% of induced women. Failed induction of labor was found to be 21%. Primiparous [AOR = 2.35 (1.35–4.09)], analgesia/anesthesia [AOR = 4.37 (1.31–14.59)], poor Bishop Score [AOR = 2.37 (1.16–4.84)], Birth weight ≥ 4 k grams [AOR = 2.12 (1.05–4.28)] and body mass index [AOR = 5.71 (3.26–10.01)] were found to be significantly associated with failed induction of labor.

Conclusion

The prevalence of failed induction of labour was found to be high. Preparation of the cervix before induction in primi-parity women is suggested to improve the success of induction. To achieve the normal weight of women and newborns, proper nutritional interventions should be given for women of reproductive age. It is better to use analgesia/anesthesia for labor induction when it becomes mandatory and there are no other optional methods of no- pharmacologic pain management.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12884-021-03862-x.

Maternal body mass index and oxytocin in augmentation of labour in nulliparous women: a prospective observational study

OBJECTIVE

To evaluate oxytocin use for augmentation of labour in relation to body mass index (BMI) on admission to the labour ward, focusing on cumulative oxytocin dose and maximum rate of oxytocin infusion during the first stage of labour.

DESIGN

Prospective observational study.

SETTING

Seven hospitals in Sweden.

PARTICIPANTS

1097 nulliparous women with singleton cephalic presentation pregnancy, ≥37 weeks of gestation, spontaneous onset of labour and treatment with oxytocin infusion for labour augmentation. The study population was classified into three BMI subgroups on admission to the labour ward: normal weight (18.5-24.9), overweight (25.0-29.9) and obese (≥30.0). The cumulative oxytocin dose was measured from the start of oxytocin infusion until the neonate was born.

PRIMARY OUTCOME

Cumulative oxytocin dose.

SECONDARY OUTCOME

Maximum rate of oxytocin infusion during the active phase of first stage of labour.

RESULTS

The mean cumulative oxytocin dose increased in the BMI groups (normal weight 2278 mU, overweight 3108 mU and obese 4082 mU (p<0.0001)). However, when adjusted for the confounders (cervical dilatation when oxytocin infusion was started, fetal birth weight, epidural analgesia), the significant difference was no longer seen. The maximum oxytocin infusion rate during the first stage of labour differed significantly in the BMI groups when adjusted for the confounding factors individually but not when adjusted for all three factors simultaneously. In addition, the maximum oxytocin infusion rate was significantly higher in women with emergency caesarean section compared with women with vaginal delivery.

CONCLUSIONS

Women with increasing BMI with augmentation of labour received a higher cumulative oxytocin dose and had a higher maximum oxytocin infusion rate during first stage of labour, however, when adjusted for relevant confounders, the difference was no longer seen. In the future, the guidelines for augmentation of labour with oxytocin infusion might be reconsidered and include modifications related to BMI.

Internal fetal and uterine monitoring in obese patients and maternal obstetrical outcomes

BACKGROUND

The maternal habitus in the setting of obesity makes external monitoring of the fetal heart rate and contractions suboptimal, and internal monitors may be utilized more often in this population. Obesity is a risk factor for obstetrical infectious complications, but it is unknown whether the use of internal monitors in this population is associated with additional risks.

OBJECTIVE

This study aimed to investigate the association between the use of an intrauterine pressure catheter and a fetal scalp electrode and maternal infectious morbidity among women with obesity.

STUDY DESIGN

This secondary analysis of a prospective cohort study included women with singleton gestations admitted for labor at ≥37 weeks' gestation at a tertiary care institution from 2010 to 2014. Obesity was defined as a body mass index of ≥30 kg/m². The primary outcome was a composite maternal infectious morbidity, which included peripartum maternal fever, chorioamnionitis, and endomyometritis. Secondary outcomes were cesarean delivery and individual components of the maternal infectious composite. Multivariable logistic regression was used to compare the rates of infectious maternal morbidity, cesarean delivery, or operative vaginal delivery between patients with and without internal monitors, while adjusting for the confounders. An interaction term was included in the logistic regression models to test whether the relationship between the internal monitors and cesarean delivery or infectious morbidity was modified by the presence or absence of obesity.

RESULTS

Of the 8482 women who met the inclusion criteria for the study, 4727 (55.7%) had obesity and 3755 (44.3%) did not have obesity. The women with obesity were more likely to have internal monitors placed during labor than those without obesity (65.4% vs 50.5%; P<.001). The use of internal monitors was associated with an increased risk for the composite maternal infectious morbidity (9.9% vs 4.1%; P<.01 and adjusted odds ratio, 2.08; 95% confidence interval, 1.70-2.55). Women with obesity had a weaker association between the use of internal monitors and maternal infectious morbidity than women without obesity (P value for interaction of .02). The incidence of cesarean delivery was also significantly higher among women who had internal monitors placed during their labor course (adjusted odds ratio, 2.84; 95% confidence interval, 2.46-3.28), and this interaction was not modified by obesity.

CONCLUSION

Although a higher proportion of women with obesity have internal monitors placed during their labor course, they are not more susceptible to maternal infectious morbidity as a result of internal monitor use. Providers should not limit the necessary internal monitor use in women with obesity on the basis of concerns for maternal infectious morbidity.

The effect of obesity on the onset of spontaneous labor and scheduled delivery rates in term pregnancies

OBJECTIVE

To determine the effect of obesity on the onset of spontaneous labor, scheduled delivery rates and perinatal outcomes in term pregnancies.

MATERIAL AND METHODS

242 obese and 244 non-obese pregnant women ≥37 gestational weeks were compared in terms of the onset of spontaneous labor, scheduled delivery rates and perinatal outcomes.

RESULTS

Obese pregnant women had statistically significantly lower onset of spontaneous labor and higher rates of scheduled delivery. No difference was determined in respect of the type of delivery, 1st and 5th minutes APGAR scores and the need for intensive care. Higher values of birth weight, large for gestational age, macrosomia, gestational diabetes mellitus and preeclampsia were determined in obese women.

CONCLUSION

The onset of spontaneous labor rates in term obese pregnancies were lower and scheduled delivery rates were higher than in the non-obese pregnancies. However, more extensive studies are needed to better understand this relationship.

The Role of Oxytocin in Primary Cesarean Birth Among Low-Risk Women

INTRODUCTION

To examine whether there is a threshold of oxytocin exposure at which the risk for primary cesarean increases among women who are nulliparous with a term, singleton, vertex fetus (NTSV) and how oxytocin interacts with other risk factors to contribute to this outcome.

METHODS

This was a secondary analysis of the Consortium on Safe Labor data set that used a retrospective cohort study design. Women who met the criteria for NTSV who were not admitted for a prelabor cesarean and for whom oxytocin data were available, were included in the sample. Robust logistic regression was used to examine the association of oxytocin exposure with primary cesarean birth, while controlling for demographic and clinical risk factors and clustering by provider.

RESULTS

The sample comprised 17,331 women who were exposed to oxytocin during labor. The women were predominantly white non-Hispanic (59.2%) with an average (SD) gestational age of 39.4 (1.1) weeks and an 18.5% primary cesarean rate. Exposure to greater than 11,400-milliunits (mU) of oxytocin resulted in 1.6 times increased odds of primary cesarean birth compared with less than 11,400 mU (95% CI 1.01-2.6).

DISCUSSION

Exposure to greater than 11,400 mU of oxytocin in labor was associated with an increased odds of primary cesarean birth in NTSV women.

Metabolic Pathways Associated With Term Labor Induction Course in African American Women

OBJECTIVES

The purpose of this study was to evaluate differences in the metabolic pathways activated in late-pregnancy serum samples among African American women who went on to have term (≥37 weeks) labor induction requiring high total oxytocin doses to complete first-stage labor compared to those in similar women with low-oxytocin labor inductions.

STUDY DESIGN

Case-control study (N = 27 women with labor induction with successful cervical ripening: 13 requiring the highest total doses of synthetic oxytocin to progress from 4- to 10-cm cervical dilation and 14 requiring the lowest total doses) with groups balanced on parity and gestational age. Serum samples obtained between 24 and 30 weeks' gestation were analyzed using ultra-high-resolution metabolomics. Differentially expressed metabolites between high-oxytocin induction cases and low-oxytocin induction comparison subjects were evaluated using linear regression with xmsPANDA. Metabolic pathways analysis was conducted using Mummichog Version 2.0, with discriminating metabolites annotated using xMSannotator Version 1.3.

RESULTS

Labor processes were similar by group with the exception that cases received over 6 times more oxytocin between 4- and 10-cm cervical dilation than comparison women. Induction requiring high total doses of synthetic oxytocin was associated with late-pregnancy serum levels of metabolites from the linoleate and fatty acid activation pathways in term, African American women.

CONCLUSION

Serum levels of several lipid metabolites predicted more complicated labor induction involving higher doses of synthetic oxytocin to complete first-stage labor. Further investigation in larger, more diverse cohorts of women is needed to identify potential targets to prevent failed labor induction.

Contractions: Traditional concepts and their role in modern obstetrics

Contractions are produced through a complex interplay of hormonal, mechanical, and electrical factors. In labor, contractions are measured using the Montevideo unit. Clinical considerations in labor wherein contraction assessment becomes paramount include the care of women whose labor is complicated by abnormal progress or tachysystole. In an era of obstetrics in which the high cesarean rate is a major issue of concern, there remain many questions as to how to best incorporate contraction monitoring into practice in order to optimize care. Technological advancement has led to the development on new modalities that can be used to study contraction physiology, and there may be an opportunity in the future to apply these methods for use in the clinical setting. This article also makes a case for the need to reevaluate the current measures of uterine contractile activity and the definition of contraction adequacy using updated definitions of normal labor progress.

An association of intrapartum synthetic oxytocin dosing and the odds of developing autism

A case-control study was performed to determine whether an association exists between exposure to synthetic oxytocin and a subsequent autism spectrum disorder diagnosis; 171 children under age 18 meeting Diagnostic and Statistical Manual of Mental Disorders (5th ed.) autism spectrum disorder criteria were compared to 171 children without autism spectrum disorder diagnosis matched by gender, birth year, gestational age, and maternal age at birth. A conditional logistic regression model was used to examine the association of clinical variables and autism spectrum disorder. Significantly elevated odds ratios for autism spectrum disorder were associated with first-time Cesarean section (odds ratio = 2.56), but not a repeat Cesarean section. Odds ratios were also significantly elevated for subjects whose mother’s body mass index was 35 or higher at birth (odds ratio = 2.34) and subjects in which the reason for delivery was categorized as “fetal indication” (odds ratio = 2.00). When controlling for these and other variables, the odds of developing autism spectrum disorder were significantly elevated in males with long duration of exposure (odds ratio = 3.48) and high cumulative dose of synthetic oxytocin (odds ratio = 2.79). No significant associations of synthetic oxytocin dosing and autism spectrum disorder were noted in female subjects. The association of elevated autism spectrum disorder odds found with high duration and high cumulative dose synthetic oxytocin in male subjects suggests the need for further investigation to fully elucidate any cause and effect relationship.

The effect of maternal body mass index on duration of induced labor

INTRODUCTION

Obese primiparous women with induction of labor are at high risk for a cesarean section. There are contradictory results regarding time in induced labor in relation to maternal body mass index (BMI). It is important to characterize the course of induced labor to prevent unnecessary cesarean section. We aimed to evaluate whether the duration of labor was associated with maternal BMI in primiparous women with induction of labor.

MATERIAL AND METHODS

A national retrospective cohort study, including 15 259 primiparae with a single term pregnancy, admitted for induction of labor from January 2014 to August 2017. Data were obtained from the Swedish Pregnancy Registry. Cox regression analyses were used to illustrate the association between BMI and active labor and between BMI and time from admission until start of active labor.

RESULTS

Duration of active labor was shorter in underweight women and prolonged in women with BMI ≥40 kg/m² compared with women in other BMI classes, illustrated by Cox regression graphs (P < .001). The median durations of active labor in underweight women were 6.1 and 7.4 hours in women with BMI ≥40 kg/m² . The time from admission until start of active labor increased with maternal BMI, illustrated by Cox regression graphs (P < .001) and the median duration increased from 12.9 hours in underweight women to 22.6 hours in women with BMI ≥40 kg/m² . The cesarean section rate in active labor increased significantly with BMI (P < .001) from 7.4% in underweight women to 22.0% in women with BMI ≥40 kg/m² . Obese and normal weight women had similar rates of spontaneous vaginal delivery (69.9% in the total study population).

CONCLUSIONS

The duration of active labor was associated with maternal BMI for underweight women and women with BMI ≥40 kg/m² . Although women with BMI ≥40 kg/m² who reached the active phase of labor had the same chance for a spontaneous vaginal delivery as normal weight women, the duration of active labor and the cesarean section rate were increased. The time from admission until start of active labor increased successively with maternal BMI.

Preventing Cesarean Birth in Women with Obesity: Influence of Unit-Level Midwifery Presence on Use of Cesarean among Women in the Consortium on Safe Labor Data Set

INTRODUCTION

Maternal obesity is associated with slow labor progression and unplanned cesarean birth. Midwives use fewer medical interventions during labor, and the women they care for have lower cesarean birth rates, compared with low-risk, matched groups of women cared for by physicians. The primary aim of this study was to examine associations between midwifery unit-level presence and unplanned cesarean birth in women with different body mass index (BMI) ranges. Unit-level presence of midwives was analyzed as a representation of a unique set of care practices that exist in settings where midwives work.

METHODS

A retrospective cohort study was conducted using Consortium on Safe Labor data from low-risk, healthy women who labored and gave birth in medical centers with (n = 9795) or without (n = 13,398) the unit-level presence of midwives. Regression models were used to evaluate for associations between unit-level midwifery presence and 1) the incidence of unplanned cesarean birth and 2) in-hospital labor durations with stratification by maternal BMI and adjustment for maternal demographic and pregnancy factors.

RESULTS

The odds of unplanned cesarean birth among women who gave birth in centers with midwives were 16% lower than the odds of cesarean birth among similar women at who gave birth at centers without midwives (adjusted odds ratio, 0.84; 95% CI, 0.77-0.93). However, women whose BMI was above 35.00 kg/m2 at labor admission had similar odds of cesarean birth, regardless of unit-level midwifery presence. In-hospital labor duration prior to unplanned cesarean was no different by unit-level midwifery presence in nulliparous women whose BMI was above 35.00 kg/m2 .

DISCUSSION

Although integration of midwives into the caregiving environment of medical centers in the United States was associated with overall decrease in the incidence of cesarean birth, increased maternal BMI nevertheless remained positively associated with these outcomes.

The Edmonton Obesity Staging System Predicts Mode of Delivery After Labour Induction

OBJECTIVE

This study sought to evaluate the use of the Edmonton Obesity Staging System (EOSS) in predicting cesarean delivery among term, nulliparous, singleton pregnancies in women with overweight or obesity who are undergoing an induction of labour.

METHODS

A prospective cohort study was performed in Edmonton, Alberta. Women undergoing an induction of labour at term were recruited to either a sample cohort, including women with a body mass index of ≥25 kg/m² at first antenatal visit, or a control cohort with a body mass index of 18.5 to 24.9 kg/m². Participating women provided a self-reported health history and consented to review of their medical records allowing allocation into EOSS categories. The primary outcome was the rate of cesarean delivery based on EOSS category. Secondary outcomes consisted of a summary score of adverse maternal, delivery, and neonatal events (Canadian Task Force Classification II-2).

RESULTS

Overall, 345 women were recruited, with a participation rate of 93.7%. The sample cohort consisted of 276 women with overweight or obesity, whereas the control cohort included 69 normal-weight women. The overall rate of cesarean delivery was 30.4% for the control cohort and 35.8%, 29.9%, 43.2%, and 90.5% for women assigned an EOSS category 0, 1, 2, and 3, respectively (P < 0.001). A summary score was not indicative of overall rate of adverse maternal, delivery, and neonatal events (P = 0.22).

CONCLUSION

The EOSS may help predict the chance of cesarean delivery in a high-risk group of nulliparous women with overweight or obesity who are undergoing an induction of labour at term.

Behavioral and epigenetic consequences of oxytocin treatment at birth

Oxytocin is used in approximately half of all births in the United States during labor induction and/or augmentation. However, the effects of maternal oxytocin administration on offspring development have not been fully characterized. Here, we used the socially monogamous prairie vole to examine the hypothesis that oxytocin exposure at birth can have long-term developmental consequences. Maternally administered oxytocin increased methylation of the oxytocin receptor (Oxtr) in the fetal brain. As adults, oxytocin-exposed voles were more gregarious, with increased alloparental caregiving toward pups and increased close social contact with other adults. Cross-fostering indicated that these effects were the result of direct action on the offspring, rather than indirect effects via postnatal changes in maternal behavior. Male oxytocin-exposed offspring had increased oxytocin receptor density and expression in the brain as adults. These results show that long-term effects of perinatal oxytocin may be mediated by an epigenetic mechanism.

Influence of Maternal Obesity on Labor Induction: A Systematic Review and Meta-Analysis

INTRODUCTION

Studies have shown that women with obesity have longer labors. The purpose of this systematic review and meta-analysis is to examine existing evidence regarding labor induction in women with obesity, including processes and outcomes. The primary outcome was cesarean birth following labor induction. Secondary outcomes were the timing and dosage of prostaglandins, the success of mechanical cervical ripening methods, and synthetic oxytocin dose and timing.

METHODS

Searches were performed in PubMed, MEDLINE, Embase, CINAHL, EBSCO, the Cochrane Database of Systematic Reviews, the Database of Abstracts of Effects, Google Scholar, and ClinicalTrials.gov. Searches were limited to studies published in English after 1990. Ten studies published between 2009 and 2017 were included in this review. All were observational studies comparing processes and outcomes of induction of labor in relation to maternal body mass index. The primary outcome was cesarean birth following labor induction. We assessed heterogeneity using Cochran's Q test and tau-squared and I² statistics. We also calculated fixed-effect models to estimate pooled relative risks and weighted mean differences.

RESULTS

Ten cohort studies met inclusion criteria; 8 studies had data available for a meta-analysis of the primary outcome. Cesarean birth was more common among women with obesity compared with women of normal weight following labor induction (Mantel-Haenszel fixed-effect odds ratio, 1.82; 95% CI, 1.55-2.12; P < .001). Maternal obesity was associated with a longer time to birth, higher doses of prostaglandins, less frequent success of cervical ripening methods, and higher dose of synthetic oxytocin, as well as a longer time to birth after oxytocin use.

DISCUSSION

Women with obesity are more likely than women with a normal weight to end labor induction with cesarean birth. Additionally, women with obesity require longer labor inductions involving larger, more frequent applications of both cervical ripening methods and synthetic oxytocin.

Maternal plasma leptin levels in relation to the duration of the active phase of labor

INTRODUCTION

Obese women have increased leptin levels and longer duration of labor compared with normal-weight women. Leptin has an inhibitory effect on myometrial contractility in vitro. Our purpose was to examine whether maternal leptin levels in active labor were associated with the duration of the active phase of labor.

MATERIAL AND METHODS

This prospective cohort study included 914 women. Maternal blood samples were collected in active labor. The plasma-leptin concentration was obtained using a direct sandwich-based ELISA. Bivariate and multiple linear regression analyses were used to study the association between leptin levels and the duration of labor.

RESULTS

A 1 ng/mL increase in maternal plasma leptin was associated with a 0.015 hour increase in duration of labor (P < .007). This association was not statistically significant in the adjusted analyses nor when analyzing nulliparous and multiparous women separately. In women with spontaneous labor (n = 766) leptin levels were not associated with an increase in duration of labor in the adjusted analyses.

CONCLUSIONS

There was no significant association between leptin levels and duration of the active phase of labor. Leptin in vivo might display a similar dose-response effect on myometrial contractility as demonstrated in in vitro studies. Future studies need to explore the association between leptin levels and time in labor in obese women with high leptin levels to evaluate a possible dose-response effect.

Association between provider type and cesarean birth in healthy nulliparous laboring women: A retrospective cohort study

BACKGROUND

Term nulliparous women have the greatest variation across hospitals and providers in cesarean rates and therefore present an opportunity to improve quality through optimal care. We evaluated associations between provider type and mode of birth, including examination of intrapartum management in healthy, laboring nulliparous women.

METHODS

Retrospective cohort study using prospectively collected perinatal data from a United States academic medical center (2005-2012). The sample included healthy nulliparous women with spontaneous labor onset and term, singleton, vertex fetus managed by either obstetricians or certified nurse-midwives. Univariate and multivariate logistic regression was used to compare labor interventions and mode of birth by provider type.

RESULTS

A total of 1339 women received care by an obstetrician (n = 749) or nurse-midwife (n = 590). The cesarean rate was 13.4% (179/1339). Adjusting for maternal and pregnancy characteristics, care by obstetricians was associated with an increased risk of unplanned cesarean birth (adjusted odds ratio [aOR] 1.48 [95% confidence interval {CI} 1.04-2.12]) compared with care by midwives. Obstetricians more frequently used oxytocin augmentation (aOR 1.41 [95% CI 1.10-1.80]), neuraxial anesthesia (aOR 1.69 [95% CI 1.29-2.23]), and operative vaginal delivery with forceps or vacuum (aOR 2.79 [95% CI 1.75-4.44]). Adverse maternal or neonatal outcomes were not different by provider type across all modes of birth, but were more frequent in women with cesarean than vaginal births.

DISCUSSION

In low-risk nulliparous laboring women, care by obstetricians compared with nurse-midwives was associated with increased risk of labor interventions and operative birth. Changes in labor management or increased use of nurse-midwives could decrease the rate of a first cesarean in low-risk laboring women.

Spontaneous Labor Onset and Outcomes in Obese Women at Term

OBJECTIVE

The objective of this study was to compare the rates of spontaneous labor onset and its progression in obese and nonobese women after 37 weeks.

STUDY DESIGN

We performed a secondary analysis of a retrospective cohort of all women who were admitted for delivery at ≥ 37 weeks of gestation at a university-based tertiary care center between 2004 and 2010. The cohort was stratified by weeks of gestation at which the patient presented for delivery. The rates of spontaneous labor, vaginal delivery, and augmentation with oxytocin were compared between obese (body mass index [BMI] ≥ 30) and nonobese (BMI < 30) women.

RESULTS

Obese women had lower rates of spontaneous labor than nonobese women at every gestational week (37 weeks, 6.1 vs. 9.3%, p < 0.001; 38 weeks, 12.8 vs. 19.2%, p < 0.001; 39 weeks 26.0 vs. 37.0%, p < 0.001; 40 weeks, 39.6 vs. 50.2%, p < 0.001; 41 weeks, 30.8 vs. 38.0%, p < 0.012). Among women who presented in spontaneous labor, obesity was associated with higher rates of augmentation with oxytocin and lower rates of vaginal delivery.

CONCLUSION

Obese women at or beyond 37 weeks are less likely to experience spontaneous labor compared with nonobese women. In addition, obese women presenting in spontaneous labor are less likely that nonobese women to have a vaginal delivery at 37 to 40 weeks, even after oxytocin augmentation.

Oxytocin and potential benefits for obesity treatment

PURPOSE OF REVIEW

Laboratory animal experiments have consistently shown that oxytocin causes early termination of food intake, thereby promoting a decrease in body weight in a long term. Recent studies have also assessed some of oxytocin's effects on appetite and energy balance in humans. The present study examines the findings of the key basic research and of the few clinical studies published thus far in the context of potential benefits and challenges stemming from the use of oxytocin in obese patients.

RECENT FINDINGS

Basic research indicates the involvement of oxytocin in satiety, processing, in reducing a drive to eat for pleasure and because of psychosocial factors. Although the results of clinical studies are very scarce, they suggest that oxytocin administered intranasally in humans decreases energy-induced and reward-induced eating, supports cognitive control of food choices, and improves glucose homeostasis, and its effectiveness may be BMI dependent.

SUMMARY

Despite the wealth of basic research showing broad anorexigenic effects of oxytocin, clinical studies on oxytocin's therapeutic potential in obesity, are still in their infancy. Future implementation of oxytocin-based pharmacological strategies in controlling energy balance will likely depend on our ability to integrate diverse behavioral and metabolic effects of oxytocin in obesity treatment regimens.

Oxytocin Augmentation in Spontaneously Laboring, Nulliparous Women: Multilevel Assessment of Maternal BMI and Oxytocin Dose

BACKGROUND

Synthetic oxytocin, the primary tool for labor augmentation, is less effective among obese women, leading to more unplanned cesarean deliveries for slow labor progress. It is not known if obese women require higher doses of oxytocin due to maternal, fetal, or labor factors related to maternal obesity.

OBJECTIVES

This study had two main objectives: (1) examine the influence of maternal body mass index (BMI) on hourly doses of oxytocin from augmentation initiation until vaginal delivery in obese women; and (2) examine the influence of other maternal, fetal, and labor factors on hourly doses of oxytocin in obese women.

STUDY DESIGN

Longitudinal study of a cohort ( N = 136) of healthy, nulliparous, spontaneously laboring obese women (BMI ≥ 30 kg/m2) who received oxytocin augmentation and achieved vaginal delivery. We performed iterative multilevel analyses to examine the influence of maternal BMI and other factors on hourly oxytocin doses.

RESULTS

Maternal BMI explained 16.56% (95% confidence interval [CI] = [13.7, 20.04], p < .001) of the variance in hourly oxytocin doses received in a multilevel model controlling for influence of maternal, fetal, and labor characteristics. Maternal age, gestational age, status of amniotic membranes at hospital admission, and admission cervical dilation examination were not significant; however, neonatal birthweight and cervical dilation at oxytocin initiation were significant predictors of hourly oxytocin dose in these women ( p < .001).

CONCLUSIONS

Even when parturition preparation has progressed adequately for spontaneous labor initiation, there still may be some obesity-related blunting of myometrial contractility and response to oxytocin used for augmentation.

Maternal body mass index and oxytocin exposure in nulliparous women: is there an interaction associated with maternal and neonatal morbidities?

OBJECTIVE

Increasing body mass index (BMI) and administered doses of oxytocin are related to maternal and neonatal morbidities. We evaluated the effect of oxytocin dosage, BMI, and their interaction on select perinatal outcomes.

STUDY DESIGN

We retrospectively studied nulliparas with singletons ≥36 weeks' gestation who received oxytocin and reached the second stage of labor. Oxytocin dosage was defined by the oxytocin product ([maximum oxytocin dose] × [duration of oxytocin infusion]/100 (milliunits)). Outcomes included cesarean, postpartum hemorrhage, puerperal infection, and a composite of neonatal morbidities. Logistic regression produced odds ratios (OR) for BMI and oxytocin product. The final model included a BMI-oxytocin product interaction term.

RESULTS

One thousand two hundred and four women met enrollment criteria. Increasing BMI was associated with longer duration from first exam to delivery and higher rates of cesarean. Oxytocin dosage increased linearly with BMI (p < .001). There were increasing odds of all four outcomes as both BMI and oxytocin dosage increased (except cesarean with oxytocin). However, there was no significant interaction between BMI and oxytocin for any outcome.

CONCLUSIONS

BMI and oxytocin dosage are associated with select maternal and neonatal outcomes. However, the lack of interaction between BMI and oxytocin product suggests that the higher administered dose of oxytocin associated with increasing BMI does not synergistically potentiate maternal and neonatal morbidities.

C-Section Prevalence Among Obese Mothers and Neonatal Hypoglycemia: a Cohort Analysis of the Department of Gynecology and Obstetrics of the University of Lübeck

INTRODUCTION

Data from the World Health Organization (WHO) demonstrates an increasing prevalence of obesity in Western countries. This study investigates the influence of obesity on the mode of delivery and the occurrence of hypoglycemia in newborns.

MATERIALS AND METHODS

A retrospective analysis of all deliveries at the Department of Gynecology and Obstetrics of the University of Lübeck, Germany was conducted over a period of eleven years with the primary outcome as non-elective C-sections and hypoglycemia of newborns from obese mothers. Patients were divided into six subgroups according to WHO weight classifications as follows: control group body mass index (BMI) 18.5 - 24.9 kg/m ² , n = 7712; general obesity BMI ≥ 25 kg/m ² , n = 4227; overweight BMI 25 - 29.9 kg/m ² , n = 2628; obesity I° BMI 30 - 34.9 kg/m ² , n = 1017; obesity II° BMI 35 - 39.9 kg/m ² , n = 370; obesity III° BMI ≥ 40 kg/m ² , n = 212.

RESULTS

Analysis of the primary outcome shows an increased incidence of non-elective C-sections with an elevated BMI (general obesity vs. control group: 20.5 vs. 15.9%, p < 0.001; OR 1.3; 95% CI 1.2 - 1.4) and elevated rates of neonatal hypoglycemia in newborns of obese mothers (general obesity vs. control group: 0.6 vs. 0.3%, p < 0.05; OR 1.8; 95% CI 1.0 - 3.0).

CONCLUSIONS

Obesity is an essential obstetric risk factor. Obese women face an increased risk of non-elective C-sections, and newborns of obese mothers suffer from elevated rates of hypoglycemia.

Titration of Intravenous Oxytocin Infusion for Postdates Induction of Labor Across Body Mass Index Groups

OBJECTIVE

To evaluate whether oxytocin titration for postdates labor induction differs among women who are normal weight, overweight, and obese and whether length of labor and birth method differ by oxytocin titration and body mass index (BMI).

DESIGN

Retrospective cohort study.

SETTING

U.S. university-affiliated hospital.

PARTICIPANTS

Of 280 eligible women, 21 were normal weight, 134 were overweight, and 125 were obese at labor admission.

METHODS

Data on women who received oxytocin for postdates induction between January 1, 2013 and June 30, 2013 were extracted from medical records. Oxytocin administration and labor outcomes were compared across BMI groups, controlling for potential confounders. Data were analyzed using χ², analysis of variance, analysis of covariance, and multiple linear and logistic regression models.

RESULTS

Women who were obese received more oxytocin than women who were overweight in the unadjusted analysis of variance (7.50 units compared with 5.92 units, p = .031). Women who were overweight had more minutes between rate changes from initiation to maximum than women who were obese (98.19 minutes compared with 83.39 minutes, p = .038). Length of labor increased with BMI (p = .018), with a mean length of labor for the normal weight group of 13.96 hours (standard deviation = 8.10); for the overweight group, 16.00 hours (standard deviation = 7.54); and for the obese group, 18.30 hours (standard deviation = 8.65). Cesarean rate increased with BMI (p = .001), with 4.8% of normal weight, 33.6% of overweight, and 42.4% of obese women having cesarean births.

CONCLUSION

Women who were obese and experienced postdates labor induction received more oxytocin than women who were non-obese and had longer length of labor and greater cesarean rates.

Labor Intervention and Outcomes in Women Who Are Nulliparous and Obese: Comparison of Nurse-Midwife to Obstetrician Intrapartum Care

BACKGROUND

Women who are obese have slower labors than women of normal weight, and show reduced response to interventions designed to speed labor progress like oxytocin augmentation and artificial rupture of membranes. The optimal labor management for these women has not been described.

METHODS

This retrospective cohort study compared 2 propensity score-matched groups of women (N = 360) who were healthy, nulliparous, spontaneously laboring, and obese (body mass index ≥ 30 kg/m2 ). Labors were managed by either a certified nurse-midwife (CNM) or an obstetrician at one hospital from 2005 through 2012. Comparisons were made on a range of labor processes and outcomes.

RESULTS

Women who were obese and cared for in labor by CNMs were 87.0% less likely to have operative vaginal birth (adjusted odds ratio [aOR], 0.15; 95% confidence interval [CI], 0.06-0.41) and 76.3% less likely to have third- or fourth-degree perineal lacerations (aOR, 0.31; 95% CI, 0.13-0.79) compared to a matched group of women who were obese and had similarly sized neonates but who were cared for by obstetricians. The rates of unplanned cesarean birth, postpartum hemorrhage, maternal intrapartum fever, and neonatal intensive care unit admission were similar between groups. CNM patients were significantly less likely than patients of obstetricians to have labor anesthesia, synthetic oxytocin augmentation, or intrauterine pressure catheters. By contrast, CNM patients were significantly more likely than patients of obstetricians to use physiologic labor interventions, including intermittent fetal monitoring, ambulation, and hydrotherapy.

DISCUSSION

In women with spontaneous labor onset who were healthy, obese, and nulliparous, watchful waiting and use of physiologic labor interventions, characterizing CNM intrapartum care, were associated with outcomes that were similar to, or better than, those of women who were obese and exposed to more high-technology interventions characterizing intrapartum care by obstetricians. In women who were obese, physiologic labor interventions were safe for both mothers and neonates.

Parturition dysfunction in obesity: time to target the pathobiology

Over a third of women of childbearing age in the United States are obese, and during pregnancy they are at increased risk for delayed labor onset and slow labor progress that often results in unplanned cesarean delivery. The biology behind this dysfunctional parturition is not well understood. Studies of obesity-induced changes in parturition physiology may facilitate approaches to optimize labor in obese women. In this review, we summarize known and proposed biologic effects of obesity on labor preparation, contraction/synchronization, and endurance, drawing on both clinical observation and experimental data. We present evidence from human and animal studies of interactions between obesity and parturition signaling in all elements of the birth process, including: delayed cervical ripening, prostaglandin insensitivity, amniotic membrane strengthening, decreased myometrial oxytocin receptor expression, decreased myocyte action potential initiation and contractility, decreased myocyte gap junction formation, and impaired myocyte neutralization of reactive oxygen species. We found convincing clinical data on the effect of obesity on labor initiation and successful delivery, but few studies on the underlying pathobiology. We suggest research opportunities and therapeutic interventions based on plausible biologic mechanisms.