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

Intrapartum exposure to synthetic oxytocin, maternal BMI, and neurodevelopmental outcomes in children within the ECHO consortium

BACKGROUND

Synthetic oxytocin (sOT) is frequently administered during parturition. Studies have raised concerns that fetal exposure to sOT may be associated with altered brain development and risk of neurodevelopmental disorders. In a large and diverse sample of children with data about intrapartum sOT exposure and subsequent diagnoses of two prevalent neurodevelopmental disorders, i.e., attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), we tested the following hypotheses: (1) Intrapartum sOT exposure is associated with increased odds of child ADHD or ASD; (2) associations differ across sex; (3) associations between intrapartum sOT exposure and ADHD or ASD are accentuated in offspring of mothers with pre-pregnancy obesity.

METHODS

The study sample comprised 12,503 participants from 44 cohort sites included in the Environmental Influences on Child Health Outcomes (ECHO) consortium. Mixed-effects logistic regression analyses were used to estimate the association between intrapartum sOT exposure and offspring ADHD or ASD (in separate models). Maternal obesity (pre-pregnancy BMI ≥ 30 kg/m2) and child sex were evaluated for effect modification.

RESULTS

Intrapartum sOT exposure was present in 48% of participants. sOT exposure was not associated with increased odds of ASD (adjusted odds ratio [aOR] 0.86; 95% confidence interval [CI], 0.71-1.03) or ADHD (aOR 0.89; 95% CI, 0.76-1.04). Associations did not differ by child sex. Among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of offspring ADHD (aOR 0.72; 95% CI, 0.55-0.96). No association was found among mothers without obesity (aOR 0.97; 95% CI, 0.80-1.18).

CONCLUSIONS

In a large, diverse sample, we found no evidence of an association between intrapartum exposure to sOT and odds of ADHD or ASD in either male or female offspring. Contrary to our hypothesis, among mothers with pre-pregnancy obesity, sOT exposure was associated with lower odds of child ADHD diagnosis.

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.

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.

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.

Maternal and newborn plasma oxytocin levels in response to maternal synthetic oxytocin administration during labour, birth and postpartum - a systematic review with implications for the function of the oxytocinergic system

BACKGROUND

The reproductive hormone oxytocin facilitates labour, birth and postpartum adaptations for women and newborns. Synthetic oxytocin is commonly given to induce or augment labour and to decrease postpartum bleeding.

AIM

To systematically review studies measuring plasma oxytocin levels in women and newborns following maternal administration of synthetic oxytocin during labour, birth and/or postpartum and to consider possible impacts on endogenous oxytocin and related systems.

METHODS

Systematic searches of PubMed, CINAHL, PsycInfo and Scopus databases followed PRISMA guidelines, including all peer-reviewed studies in languages understood by the authors. Thirty-five publications met inclusion criteria, including 1373 women and 148 newborns. Studies varied substantially in design and methodology, so classical meta-analysis was not possible. Therefore, results were categorized, analysed and summarised in text and tables.

RESULTS

Infusions of synthetic oxytocin increased maternal plasma oxytocin levels dose-dependently; doubling the infusion rate approximately doubled oxytocin levels. Infusions below 10 milliunits per minute (mU/min) did not raise maternal oxytocin above the range observed in physiological labour. At high intrapartum infusion rates (up to 32 mU/min) maternal plasma oxytocin reached 2-3 times physiological levels. Postpartum synthetic oxytocin regimens used comparatively higher doses with shorter duration compared to labour, giving greater but transient maternal oxytocin elevations. Total postpartum dose was comparable to total intrapartum dose following vaginal birth, but post-caesarean dosages were higher. Newborn oxytocin levels were higher in the umbilical artery vs. umbilical vein, and both were higher than maternal plasma levels, implying substantial fetal oxytocin production in labour. Newborn oxytocin levels were not further elevated following maternal intrapartum synthetic oxytocin, suggesting that synthetic oxytocin at clinical doses does not cross from mother to fetus.

CONCLUSIONS

Synthetic oxytocin infusion during labour increased maternal plasma oxytocin levels 2-3-fold at the highest doses and was not associated with neonatal plasma oxytocin elevations. Therefore, direct effects from synthetic oxytocin transfer to maternal brain or fetus are unlikely. However, infusions of synthetic oxytocin in labour change uterine contraction patterns. This may influence uterine blood flow and maternal autonomic nervous system activity, potentially harming the fetus and increasing maternal pain and stress.

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.

Oxytocin and Related Peptide Hormones: Candidate Anti-Inflammatory Therapy in Early Stages of Sepsis

Sepsis is a potentially life-threatening systemic inflammatory syndrome characterized by dysregulated host immunological responses to infection. Uncontrolled immune cell activation and exponential elevation in circulating cytokines can lead to sepsis, septic shock, multiple organ dysfunction syndrome, and death. Sepsis is associated with high re-hospitalization and recovery may be incomplete, with long term sequelae including post-sepsis syndrome. Consequently, sepsis continues to be a leading cause of morbidity and mortality across the world. In our recent review of human chorionic gonadotropin (hCG), we noted that its major properties including promotion of fertility, parturition, and lactation were described over a century ago. By contrast, the anti-inflammatory properties of this hormone have been recognized only more recently. Vasopressin, a hormone best known for its anti-diuretic effect, also has anti-inflammatory actions. Surprisingly, vasopressin's close cousin, oxytocin, has broader and more potent anti-inflammatory effects than vasopressin and a larger number of pre-clinical studies supporting its potential role in limiting sepsis-associated organ damage. This review explores possible links between oxytocin and related octapeptide hormones and sepsis-related modulation of pro-inflammatory and anti-inflammatory activities.

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.

Cervical Ripening and Labor Induction and Augmentation, 5th Edition

Cervical ripening and induction and augmentation of labor are common procedures in labor and birth units. The potential risks and benefits for the procedure should be explained to women so that they can make informed decisions. Clinicians should be knowledgeable about the methods and medications used and be skilled in maternal-fetal assessment. Adequate nurse staffing is required to monitor the mother and fetus to promote the best possible outcomes. This practice monograph includes information on mechanical and pharmacologic methods for cervical ripening; labor induction and augmentation with oxytocin, a high alert drug; and nurse staffing levels and skills needed to provide safe and effective care during cervical ripening and labor induction and augmentation.

Birth Outcomes of Women with Obesity Enrolled for Care at Freestanding Birth Centers in the United States

Introduction

Current US guidelines for the care of women with obesity generalize obesity‐related risks to all women regardless of overall health status and assume that birth will occur in hospitals. Perinatal outcomes for women with obesity in US freestanding birth centers need documentation.

Methods

Pregnancies recorded in the American Association of Birth Centers Perinatal Data Registry were analyzed (n = 4,455) to form 2 groups of primiparous women (n = 964; 1:1 matching of women with normal body mass indices [BMIs] and women with obese BMIs [>30]), using propensity score matching to address the imbalance of potential confounders. Groups were compared on a range of outcomes. Differences between groups were evaluated using χ² test for categorical variables and Student's t test for continuous variables. Paired t test and McNemar's test evaluated the differences among the matched pairs.

Results

The majority of women with obese BMIs experienced uncomplicated perinatal courses and vaginal births. There were no significant differences in antenatal complications, proportion of prolonged pregnancy, prolonged first and second stage labor, rupture of membranes longer than 24 hours, postpartum hemorrhage, or newborn outcomes between women with obese BMIs and normal BMIs. Among all women with intrapartum referrals or transfers (25.3%), the primary indications were prolonged first stage or second stage (55.4%), inadequate pain relief (14.8%), client choice or psychological issue (7.0%), and meconium (5.3%). Primiparous women with obesity who started labor at a birth center had a 30.7% transfer rate and an 11.1% cesarean birth rate.

Discussion

Women with obese BMIs without medical comorbidity can receive safe and effective midwifery care at freestanding birth centers while anticipating a low risk for cesarean birth. The risks of potential, obesity‐related perinatal complications should be discussed with women when choosing place of birth; however, pregnancy complicated by obesity must be viewed holistically, not simply through the lens of obesity.

Cervical Ripening and Labor Induction and Augmentation, 5th Edition

Cervical ripening and induction and augmentation of labor are common procedures in labor and birth units. The potential risks and benefits for the procedure should be explained to women so that they can make informed decisions. Clinicians should be knowledgeable about the methods and medications used and be skilled in maternal-fetal assessment. Adequate nurse staffing is required to monitor the mother and fetus to promote the best possible outcomes. This practice monograph includes information on mechanical and pharmacologic methods for cervical ripening; labor induction and augmentation with oxytocin, a high alert drug; and nurse staffing levels and skills needed to provide safe and effective care during cervical ripening and labor induction and augmentation.

Maternal and system characteristics, oxytocin administration practices, and cesarean birth rate

BACKGROUND

The cesarean birth rate in the United States is 32%, and there is discussion about the cause of high surgical birth rates. Our purpose was to determine whether mode of birth is influenced by maternal, nurse, and system factors.

METHODS

Secondary analysis of a data set of 163 women having postdates labor induction with oxytocin. Kaplan-Meier survival curves were calculated to compare the time for patients to reach an infusion rate of 6 mU/min, consistent with endogenous oxytocin levels in active labor. We used the log-rank test to evaluate survival curve differences. Multiple logistic regression and Cox proportional hazards models were conducted and included covariates that had statistically significant bivariate relationships with the time variable, or were clinically meaningful.

RESULTS

The mean time to reach 6 mU/min was longer for women who birthed by cesarean (172.5 minutes) than for women who had vaginal birth (125.0 minutes, P = .024). The mean time to reach 6 mU/min was also longer for women admitted on night shift (147.0 minutes) than day shift (110.2 minutes, P = .018). No maternal characteristics were significantly related to the time to reach a rate of 6 mU/min.

CONCLUSIONS

Even during the initial hours of labor induction, it is important that the oxytocin infusion is titrated appropriately to aid women in achieving timely vaginal birth. Intrapartum nurses should receive education about the pharmacokinetics of intravenous oxytocin to understand proper administration of this high-alert medication.

The association between delayed amniotomy and adverse outcomes in labor induction

OBJECTIVE

To assess if delayed amniotomy during labor induction is associated with adverse delivery outcomes.

STUDY DESIGN

Retrospective cohort study of women with a viable, singleton gestation who underwent labor induction at a tertiary-care hospital (4/2014-3/2017). Women were excluded if oxytocin was not used or if spontaneous rupture of membranes (ROM) occurred ≤8 h after oxytocin initiation. The primary outcome was cesarean delivery, and secondary outcomes included postpartum hemorrhage, maternal infectious morbidity, neonatal 5-min Apgar score <7, and neonatal intensive care unit admission. Women were compared by timing of amniotomy: delayed (ROM > 8 h after oxytocin initiation) versus not delayed. Multivariable logistic regression was used to estimate the association between delayed amniotomy and study outcomes.

RESULTS

Of 2081 women who met inclusion criteria, 1125 (before 54%) had delayed amniotomy. Women with delayed amniotomy had ROM 12.7 h (IQR 10.0, 17.9) after oxytocin versus 5.0 h (IQR 3.7, 6.5) without delayed amniotomy. In multivariable regression, delayed amniotomy was associated with increasingly higher odds of cesarean as maternal obesity severity increased (aOR 1.58, 95 %CI 1.24-2.03 at BMI 30 kg/m²; aOR 2.15, 95 %CI 1.45-3.21 at BMI 40 kg/m²; aOR 2.93, 95 %CI 1.54-5.57 at BMI 50 kg/m²).

CONCLUSION

Delayed amniotomy >8 h after starting oxytocin for labor induction was associated with higher odds of cesarean delivery. Significant delay in ROM should be avoided during labor induction.

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.