Nonmedically indicated induction in morbidly obese women is not associated with an increased risk of cesarean delivery

Impact of the ARRIVE Trial in Nulliparous Individuals with Morbid Obesity: Interrupted Time Series Analysis

OBJECTIVE

 We aimed to examine rates of induction of labor at 39 weeks and cesarean delivery before and after the ARRIVE (A Randomized Trial of Induction Versus Expectant Management) trial stratified by body mass index (BMI; kg/m2) category.

STUDY DESIGN

 This was a repeated cross-sectional analysis of publicly available U.S. birth certificate data from 2015 to 2021. We limited analyses to nulliparous individuals with a singleton pregnancy, cephalic presentation, without chronic hypertension, diabetes (gestational or pregestational), and fetal anomaly who delivered between 39 and 42 weeks' gestation. The pre-ARRIVE period spanned from August 2016 to July 2018 and the post-ARRIVE period spanned from January 2019 to December 2020. The dissemination period of the ARRIVE trial was from August 2018 to December 2018. Our co-primary outcomes were induction at 39 weeks and cesarean delivery. Our secondary outcomes were overall induction of labor and preeclampsia. We conducted an interrupted time series analysis after stratifying by prepregnancy BMI (<40 or ≥40). Negative binomial regression was used to calculate adjusted incident rate ratios with 95% confidence intervals.

RESULTS

 Of 2,122,267 individuals that were included, 2,051,050 had BMI <40 and 71,217 had BMI ≥40. In individuals with BMI <40, the post-ARRIVE period compared to the pre-ARRIVE period was associated with an increased rate of induction of labor at 39 weeks, a decreased rate of cesarean delivery, and an increased rate of overall induction of labor. In individuals with BMI ≥40, the post-ARRIVE period compared to the pre-ARRIVE period was associated with an increased rate of induction of labor at 39 weeks, an increased rate of overall induction of labor and a decreased rate of preeclampsia; however, the decrease in the rate of cesarean delivery was not significant.

CONCLUSION

 An increase in induction of labor at 39 weeks' gestation in individuals with BMI ≥40 was not associated with a decrease in the cesarean delivery rate.

KEY POINTS

· The ARRIVE trial increased 39-week labor inductions in BMI <40 and ≥40.. · BMI <40 had fewer cesareans; BMI ≥40 showed no significant decrease.. · Offering labor induction is reasonable as cesarean rates didn't increase..

An Externally Validated Model to Predict Prolonged Induction of Labor with an Unfavorable Cervix

OBJECTIVE

 To develop and externally validate a prediction model to calculate the likelihood of prolonged induction of labor (induction start to delivery time > 36 hours).

STUDY DESIGN

 This was a retrospective cohort study of all nulliparous women with singleton pregnancies and vertex presentation at term who underwent induction of labor and had a vaginal delivery at a single academic center. Women with contraindications for vaginal delivery were excluded. Analyses were limited to women with unfavorable cervix (both simplified Bishop score [dilation, station, and effacement: range 0-9] <6 and cervical dilation <3 cm). Prolonged induction of labor was defined as the duration of induction (induction start time to delivery) longer than 36 hours. A backward stepwise logistic regression analysis was used to identify the factors associated with prolonged induction of labor by considering maternal characteristics and comorbidities as well as fetal conditions. The final model was validated using an external dataset of the Consortium on Safe Labor after applying the same inclusion and exclusion criteria. We developed a receiver observer characteristic curve with area under the curve (AUC) in validation cohorts.

RESULTS

 Of 2,118 women, 364 (17%) had prolonged induction of labor. Factors associated with prolonged induction of labor included body mass index at admission, hypertension, fetal conditions, and epidural. Factors including younger maternal age, prelabor rupture of membranes, and a more favorable simplified Bishop score were associated with a decreased likelihood of prolonged induction of labor. In the external validation cohort, 4,418 women were analyzed, of whom 188 (4%) had prolonged induction of labor. The AUC of the final model was 0.76 (95% confidence interval: 0.73-0.80) for the external validation cohort. The online calculator was created and is available at: https://medstarapps.org/obstetricriskcalculator.

CONCLUSION

 Our externally validated model was efficient in predicting prolonged induction of labor with an unfavorable cervix.

KEY POINTS

· The number of inductions of labor at 39 weeks' gestation and beyond has been increasing.. · Our model had a good prediction of prolonged induction of labor.. · An online calculator has been created and available..

Perinatal Morbidity in Healthy Obese Pregnant Individuals Delivered by Elective Repeat Cesarean at Term

OBJECTIVE

This study aimed to compare the risks of adverse perinatal outcomes by body mass index (BMI) categories in healthy pregnant individuals delivered by term elective repeat cesarean (ERCD) to describe an optimal timing of delivery in otherwise healthy patients at the highest-risk BMI threshold.

STUDY DESIGN

A secondary analysis of a prospective cohort of pregnant individuals undergoing ERCD at 19 centers in the Maternal-Fetal Medicine Units Network from 1999 to 2002. Nonanomalous singletons undergoing prelabor ERCD at term were included. The primary outcome was composite neonatal morbidity; secondary outcomes included composite maternal morbidity and individual components of the composites. Patients were stratified by BMI classes and to identify a BMI threshold for which morbidity was the highest. Outcomes were then examined by completed week's gestation, between BMI classes. Multivariable logistic regression was used to calculate adjusted odds ratios (aOR) and 95% confidence intervals (CI).

RESULTS

A total of 12,755 patients were included in analysis. Patient's with BMI ≥ 40 had the highest rates of newborn sepsis, neonatal intensive care unit admissions, and wound complications. While a weight-related response was observed between BMI class and neonatal composite morbidity (p < 0.001), only those with BMI ≥ 40 had significantly higher odds of composite neonatal morbidity (aOR: 1.4, 95% CI: 1.0-1.8). In analyses of patients with BMI ≥ 40 (n = 1,848), there was no difference in the incidence of composite neonatal or maternal morbidity across weeks' gestation at delivery; however, as gestational age approached 39 to 40 weeks, rates of adverse neonatal outcomes decreased, only to increase again at 41 weeks' gestation. Of note, the odds of the primary neonatal composite were the highest at 38 weeks compared with 39 weeks (aOR: 1.5, 95% CI: 1.1-2.0).

CONCLUSION

Neonatal morbidity is significantly higher in pregnant individuals with BMI ≥40 delivering by ERCD. Despite this increased perinatal morbidity, delivery prior to 39 and after 41 weeks in these patients is associated with increased neonatal risks.

KEY POINTS

· Obese patients without additional comorbidities have higher rates of neonatal morbidity.. · Patients with BMI ≥ 40 carry the highest odds of poor perinatal outcomes.. · Earlier timing of delivery does not appear to reduce this risk..

Mediating processes underlying the associations between maternal obesity and the likelihood of cesarean birth

BACKGROUND

Pregnant women with obesity are more likely to experience cesarean birth compared to women without obesity. Yet, little is known about the underlying mechanisms. The objective of this study was therefore to evaluate how mediators contribute to the association between obesity and prelabor/intrapartum cesarean birth.

METHODS

We retrospectively analyzed Swiss cohort data from 394,812 singleton, cephalic deliveries between 2005 and 2020. Obesity (BMI ≥ 30 kg/m2 ) was defined as the exposure and prelabor or intrapartum cesarean birth as the outcomes. Hypothesized mediators included gestational comorbidities, large-for-gestational-age infant, pregnancy duration >410/7 weeks, slower labor progress, labor induction, and history of cesarean birth. We performed path analyses using generalized structural equation modeling and assessed mediation by a counterfactual approach.

RESULTS

Women with obesity had a cesarean birth rate of 39.36% vs. 24.12% in women without obesity. The path models mainly showed positive direct and indirect associations between obesity and cesarean birth. In the total sample, the mediation models explained up to 39.47% (95% CI 36.92-42.02) of the association between obesity and cesarean birth, and up to 57.13% (95% CI 54.10-60.16) when including history of cesarean birth as mediator in multiparous women. Slower labor progress and history of cesarean birth were found to be the most clinically significant mediators.

CONCLUSIONS

This study provides empirical insights into how obesity may increase cesarean birth rates through mediating processes. Particularly allowing for a slower labor progress in women with obesity might reduce cesarean birth rates and prevent subsequent repeat cesarean births in multiparous women.

Challenges in timing and mode of delivery in morbidly obese women

Globally obesity is increasing especially in the reproductive age group. Pregnant women with obesity have higher complication and intervention rates. They are also at increased risk of stillbirth and intrapartum complications. Although organisations like NICE, RCOG, ACOG and WHO have published guidelines and recommendations on care of pregnant women with obesity the evidence from which Grade A recommendations can be made on timing and how to deliver is limited. The current advice is therefore to have discussions with the woman on risks to help her make an informed decision about timing, place, and mode of delivery. Obesity is an independent risk factor for pregnancy complications including diabetes, hypertension and macrosomia. In those with these complications, the timing of delivery is often influenced by the severity of the complication. As an independent factor, population based observational studies in obese women have shown an increase in the risk of stillbirth. This risk increases linearly with weight from overweight through to class II obesity, but then rises sharply in those with class III obesity by at least 10-fold beyond 42 weeks when compared to normal weight women. This risk of stillbirth is notably higher in obese women from 34 weeks onwards compared to normal weight women. One modifiable risk factor for stillbirth as shown from various cohorts of pregnant women is prolonged pregnancy. Research has linked obesity to prolonged pregnancy. Although the exact mechanism is yet unknown some have linked this to maternal dysregulation of the hypothalamic pituitary adrenal axis leading to hormonal imbalance delaying parturition. For these women the two dilemmas are when and how best to deliver. In this review, we examine the evidence and make recommendations on the timing and mode of delivery in women with obesity. For class I obese women there are no differences in outcome with regards to timing and mode of delivery when compared to lean weight women. However, for class II and III obesity, planned induction or caesarean sections may be associated with a lower perinatal morbidity and mortality although this may be associated with an increased in maternal morbidity especially in class III obesity. Studies have shown that delivery by 39 weeks is associated with lower perinatal mortality compared to delivering after in these women. On balance the evidence would favour planned delivery (induction or caesarean section) before 40 weeks of gestation. In the morbidly obese, apart from the standard lower transverse skin incision for CS, there is evidence that a supraumbilical transverse incision may reduce morbidity but is less cosmetic. Irrespective of the option adopted, it is important to discuss the pros and cons of each.

Full-term induction of labor vs expectant management and cesarean delivery in women with obesity; systematic review and meta-analysis

OBJECTIVE

This study aimed to review the literature comparing full-term induction of labor with expectant management in women with obesity on the risk of cesarean delivery and other adverse outcomes.

DATA SOURCES

A literature search was performed on PubMed, EMBASE, Scopus, ClinicalTrials.gov, and the Cochrane Library. This study had no time, language, or geographic restriction.

STUDY ELIGIBILITY CRITERIA

Studies were eligible if (1) they were cohort or randomized controlled trials, (2) they compared induction of labor at early or late term with expectant management, and (3) they included women with a body mass index of ≥30 kg/m². Studies restricted to women with multiple pregnancy, premature rupture of membranes, or noncephalic presentation were excluded. The primary outcome was cesarean delivery. The secondary outcomes included maternal and neonatal mortality and morbidities and were evaluated.

METHODS

The risk of bias was assessed by 2 authors using the Risk of Bias In Non-Randomized Studies of Interventions tool. Only studies assessed with low or moderate risk of bias contributed to the meta-analysis. Data were combined to pooled relative risks and 95% confidence intervals using random effects models. The quality of evidence was assessed for selected outcomes.

RESULTS

Of the 232 studies identified, 13 were aligned with the inclusion criteria, and 4 cohort studies, including 216,318 women with induction of labor and 1,122,769 women managed expectantly, were included in the meta-analysis for the primary outcome. In women with obesity, full-term induction of labor was associated with a lower risk of cesarean delivery than expectant management (19.7% vs 24.5%; relative risk, 0.71; 95% confidence interval, 0.63-0.81). Moreover, this study found the same direction of the association for other selected outcomes: severe perineal lacerations (relative risk, 0.65; 95% confidence interval, 0.48-0.89), maternal infection (relative risk, 0.42; 95% confidence interval, 0.21-0.84), perinatal mortality (relative risk, 0.41; 95% confidence interval, 0.18-0.90), low Apgar score (relative risk, 0.48; 95% confidence interval, 0.26-0.91), meconium aspiration syndrome (relative risk, 0.40; 95% confidence interval, 0.28-0.56), and macrosomia (relative risk, 0.57; 95% confidence interval, 0.43-0.75). Conversely, induction of labor was associated with an increased risk of instrumental vaginal delivery (relative risk, 1.12; 95% confidence interval, 1.02-1.22). The quality of evidence ranged from low to very low.

CONCLUSION

Full-term induction of labor in women with obesity may reduce the risk of cesarean delivery compared with expectant management, but the quality of the evidence is low.

Elective Induction of Labour at 39 Weeks Compared With Expectant Management in Nulliparous Persons Delivering in a Community Hospital

OBJECTIVE

To determine the impact of offering elective labour induction at 39 weeks gestation on perinatal and maternal outcomes in nulliparous people with low-risk pregnancies.

METHODS

The charts of all pregnant people who delivered at Brockville General Hospital between September 2018 and December 2021 were retrospectively reviewed. Perinatal and maternal outcomes of low-risk nulliparous pregnant people who underwent elective induction at 39 weeks and over were extracted and compared with those of low-risk nulliparous pregnant people who underwent expectant management. Exclusion criteria included multiparous people, high-risk pregnancies, multiple gestations, deliveries at less than 39 weeks gestation, and elective cesarean deliveries. Univariate and multivariate analysis was performed.

RESULTS

A total of 174 patients were included. Of these patients, 56 (32.2%) underwent elective induction of labour between 39⁰ and 39⁶ weeks gestation over the period of June 2020 to December 2021, whereas 118 (67.8%) were expectantly managed from 39⁰ weeks gestation over the period of September 2018 to March 2020. Compared with expectant management, those in the 39⁺ weeks induction group had a significantly lower risk of cesarean delivery (odds ratio [OR] 0.39; 95% confidence interval [CI] 0.15-0.99), composite adverse maternal outcomes (OR 0.34; 95% CI 0.12-0.97), and composite adverse perinatal outcomes (OR 0.26; 95% CI 0.074-0.92).

CONCLUSION

Our results suggest that elective induction of labour at 39 weeks gestation and over in low-risk nulliparous people is associated with lower risks of cesarean delivery, composite adverse maternal outcomes, and composite adverse perinatal outcomes than expectant management.

Term Labor Induction and Cesarean Delivery Risk among Obese Women with and without Comorbidities

OBJECTIVE

Findings of the recent ARRIVE (A Randomized Trial of Induction Versus Expectant Management) trial, showing reduced cesarean risk with elective labor induction among low-risk nulliparous women at 39 weeks' gestation, have the potential to change interventional delivery practices but require examination in wider populations. The aim of this study was to identify whether term induction of labor was associated with reduced cesarean delivery risk among women with obesity, evaluating several maternal characteristics associated with obesity, induction, and cesarean risk.

STUDY DESIGN

We studied administrative records for 66,280 singleton, term births to women with a body mass index ≥30, without a prior cesarean delivery, in New York City from 2008 to 2013. We examined elective inductions in 39 and 40 weeks' gestation and calculated adjusted risk ratios for cesarean delivery risk, stratified by parity and maternal age. We additionally evaluated medically indicated inductions at 37 to 40 weeks among women with obesity and diabetic or hypertensive disorders, comorbidities that are strongly associated with obesity.

RESULTS

Elective induction of labor was associated with a 25% (95% confidence interval: 19-30%) lower adjusted risk of cesarean delivery as compared with expectant management at 39 weeks of gestation and no change in risk at 40 weeks. Patterns were similar when stratified by parity and maternal age. Risk reductions in week 39 were largest among women with a prior vaginal delivery. Women with comorbidities had reduced cesarean risk with early term induction and in 39 weeks.

CONCLUSION

Labor induction at 39 weeks was consistently associated with reduced risk of cesarean delivery among women with obesity regardless of parity, age, or comorbidity status. Cesarean delivery findings from induction trials at 39 weeks among low-risk nulliparous women may generalize more broadly across the U.S. obstetric population, with potentially larger benefit among women with a prior vaginal delivery.

KEY POINTS

· We found reduced cesarean risk with induction at 39 weeks.. · Results were consistent for age and comorbidity subgroups.. · Risk reductions were largest among multiparous women..

Nonovert disseminated intravascular coagulation (DIC) in pregnancy: a new scoring system for the identification of patients at risk for obstetrical hemorrhage requiring blood product transfusion

BACKGROUND

Nonovert disseminated intravascular coagulation (DIC) is a subclinical hemostatic dysfunction that has not yet reached the decompensation stage. The detection of pregnant patients at this stage may assist in the identification of those who will develop severe obstetrical hemorrhage, as it is one of the leading causes for preventable maternal mortality. Currently, nonovert DIC is diagnosed by a scoring system based on nonpregnant patients, originally generated by the International Society on Thrombosis and Hemostasis (ISTH), which does not address the physiologic changes of the hemostatic system during pregnancy.

OBJECTIVES

(1) To develop a pregnancy-specific nonovert DIC score, (2) to determine the diagnostic performance of this score in detecting women at risk for obstetrical hemorrhage requiring blood product transfusion, and (3) to compare it to the existing ISTH nonovert DIC score.

STUDY DESIGN

This retrospective study has longitudinal and cross-sectional components and includes three steps: (1) characterization of the longitudinal changes in the components of modified ISTH nonovert DIC scores, including these parameters - fibrinogen, antithrombin III, protein C, prothrombin time (PT), platelets, thrombin-antithrombin (TAT) complex, and D-dimer - during gestation in a group of normal pregnancies (n = 50); (2) development of a pregnancy-specific nonovert DIC score in a cross-sectional design of high-risk (n = 152) and control (n = 50) pregnancies, based on the predictive performance of each analyte for the detection of women at risk for obstetrical hemorrhage requiring blood product transfusion and a logistic regression model; and (3) comparison between the diagnostic performance of the pregnancy-specific nonovert DIC score and the modified ISTH nonovert DIC score to detect, upon admission, women who are at increased risk for subsequent development of obstetrical hemorrhage requiring blood product transfusion.

RESULTS

(1) The study cohort included 202 patients, of which 21 (10%) had obstetrical hemorrhage that required blood product transfusion and were considered to have nonovert DIC; (2) using the nonpregnant ISTH nonovert DIC score, 92% of the patients had a D-dimer concentration above the 0.5 mg/L threshold, and only 2% were identified to have a low fibrinogen concentration (<100 mg/dL); thus, this scoring system was unable to identify any of the patients with nonovert DIC based on the suggested cutoff of a score of ≥5; (3) the parameters included in the pregnancy-specific nonovert DIC score were selected based on their contribution to the performance of the model for the prediction of women at risk for obstetrical hemorrhage requiring blood product transfusion; as a result, we excluded the PT difference parameter from the score and the TAT complex concentration was added; and (4) a pregnancy-specific nonovert DIC score of ≥3 had a sensitivity of 71.4% and a specificity of 77.9% to identify patients at risk for obstetrical hemorrhage requiring blood product transfusion.

CONCLUSION

We propose (1) a pregnancy-specific nonovert DIC score adjusted for the physiologic changes in the hemostatic system during gestation; and (2) that the pregnancy-specific nonovert DIC score can be a useful tool for the identification of patients at risk for obstetrical hemorrhage requiring blood product transfusion.

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.

Induction of labor at 39 weeks and risk of cesarean delivery among obese women: a retrospective propensity score matched study

OBJECTIVES

To evaluate if induction of labor (IOL) in obese women at 39 weeks of gestation decreases the risk of cesarean delivery (CD).

METHODS

We conducted a retrospective propensity score matched study using the Center for Disease Control's (CDC's) Period Linked Birth-Infant Death data. The study population consisted of cephalic singleton births to women with BMI greater or equal to 30.0 kg/m² who delivered at or beyond 39 weeks between 2013 and 2017. Women with prior CD were excluded. Women who underwent IOL at 39 weeks were propensity score matched 1:5 on the basis of CD risk factors to women who did not undergo IOL at 39 weeks but may have had an IOL at a later gestational age. Conditional logistic regression compared CD rates and maternal outcomes between obese women induced at 39 weeks with those not induced at 39 weeks.

RESULTS

Our cohort consisted of 197,343 obese women induced at 39 weeks and 986,715 obese women not induced at 39 weeks. Overall, the risk of CD among women who had an IOL at 39 weeks was lower than those without an IOL at 39 weeks, 0.59 (0.58-0.60). The decrease in CD risk was more pronounced in multiparas, 0.47 (0.46-0.49) than nulliparas, 0.81 (0.79-0.83). When stratified by BMI, the effect of IOL on lowering CD risk was similar across all obesity classes. Aside from an increased risk of instrumental deliveries, morbidities were comparable in both groups.

CONCLUSIONS

IOL at 39 weeks among obese women appears to lower the risk of CD, without compromising maternal outcomes.

Induction of labour from 39 weeks in low-risk multiparas with ripe cervixes: A randomised controlled trial

BACKGROUND

Induction of labour (IOL) in low-risk nulliparas at 39 weeks reduces caesarean delivery. Multiparas with ripe cervixes typically have vaginal delivery within eight hours. Delivery at night and weekend are associated with higher maternal and neonatal mortality.

AIMS

To evaluate IOL in full-term multiparas with ripe cervixes to achieve delivery at normal working hours and improve maternal satisfaction.

METHODS

A randomised trial was performed in a tertiary hospital in Malaysia. Low-risk multiparas with ripe cervixes (Bishop score ≥6) were recruited at 38⁺⁴ -40⁺⁰  weeks, then randomised to planned labour induction at 39⁺⁰  weeks or expectant care. Primary outcomes were delivery during 'normal working hours' 09:00-17:00 hours, Monday-Friday and patient satisfaction by visual numerical rating scale.

RESULTS

For IOL (n = 80) vs expectant care (n = 80) arms respectively, primary outcomes of delivery at normal working hours was 27/80 (34%) vs 29/78 (37%), relative risk (RR) 0.9, 95% CI 0.5-1.7, P = 0.41, patient satisfaction was 8.0 ± 1.8 vs 7.8 ± 1.6, P = 0.41; presentation for spontaneous labour or rupture of membranes were 27/80 (34%) vs 70/79 (89%), RR 0.4, 95% CI 0.3-0.5, P < 0.001; and for labour induction 52/80 (65%) vs 15/79 (19%), RR 3.4, 95% CI 2.1-5.5, P < 0.001. Caesarean delivery was 8/80 (10%) vs 4/79 (5%), RR 2.0, 95% CI 0.62-6.3, P = 0.25; and mean birthweight was 3.1 ± 0.3 vs 3.3 ± 0.4 kg, P = 0.06 for IOL vs expectant care, respectively.

CONCLUSION

Labour induction in low-risk multiparas does not increase births during working hours or improve patient satisfaction. Antenatal clinic visits and non-birth hospitalisation were significantly reduced.

Effect of maternal age on emergency cesarean section

Objectives: This study aims to investigate the independent influence of maternal age on the risk of emergency cesarean section (CS) due to nonreassuring fetal heart rate or arrest disorder.Methods: This was a cross-sectional study on women with nulliparous pregnancies, who are attempting vaginal delivery at term and have a cephalic presentation without the indication of elective CS at the onset of labor. The primary outcome was the rate of emergency CS. Independent risk factors were elucidated using multivariate logistic regression analysis.Results: Of 3513 women, 541 (15.4%) delivered by emergency CS during a trial of vaginal delivery, with theses being due to nonreassuring fetal heart rate (N = 150) or arrest disorder (N = 391). In univariate analysis, both individual CS rate due to nonreassuring fetal heart rate or arrest disorder and total emergent CS rate increased with maternal age. The risk of emergency CS was also significantly higher when labor induction was performed (odds ratio (OR) 2.489, 95% confidence interval (CI) 2.043-3.033), while fetal weight was heavier (neonatal weight ≥3.5 kg; OR 2.396, 95% CI 1.956-2.934), and maternal BMI was higher (before pregnancy ≥25 kg/m²; OR 2.751, 95% CI 1.980-3.823, at delivery ≥28 kg/m²; OR 2.375 95% CI 1.915-2.946). Multivariate stepwise regression analysis showed a statistically significant increase in the risk of total emergency CS in mothers over 35 years of age, compared to that in women less than 30 years old (35-39 years group; adjusted OR 1.805 95% CI 1.347-2.418, ≥40 years group; adjusted OR 4.659 95% CI 2.709-8.013). CS due to nonreassuring fetal heart rate increased in mothers over 40 years of age (adjusted OR 5.354, 95% CI 2.386-12.017) and CS due to arrest disorder was also increased in mothers over 30 years of age (30-34 years group; adjusted OR 1.343, 95% CI 1.010-1.785, 35-39 years group; adjusted OR 1.906, 95% CI 1.357-2.679, ≥40 years group; adjusted OR 4.663, 95% CI 2.480-8.768). Similar to the result of univariate analysis, labor induction increased the risk of emergency CS (adjusted OR 2.241, 95% CI 1.828-2.747).Conclusions: Advanced maternal age is an independent risk factor of emergency CS due to nonreassuring fetal heart rate or arrest disorder during the trial of vaginal delivery. The risk of emergency CS was also increased when labor induction was performed. Therefore, the risk of emergency CS needs to be considered, especially when the labor induction is planned, in women aged 40 or more.

Risk Factors Associated With Cesarean Delivery After Induction of Labor in Women With Class III Obesity

OBJECTIVE

To assess the risk factors associated with cesarean delivery in women with class III obesity (body mass index [BMI, calculated as weight in kilograms divided by height in meters squared] 40 or higher) who are undergoing induction of labor.

METHODS

This was a retrospective cohort of obese women with a BMI of 40 or higher and singleton pregnancy of 34 weeks of gestation or longer who underwent induction of labor at two large teaching institutions from January 2013 to December 2015. The primary outcome was cesarean delivery. Secondary outcomes included maternal and neonatal composite morbidity. We then assessed the applicability of using a previously developed calculator to predict the risk of cesarean delivery. The area under the receiver operating characteristic (ROC) curve was used as a measure of the ability of the calculator to discriminate between women who underwent cesarean compared with vaginal delivery.

RESULTS

There were 485 women with class III obesity who underwent induction during the study period. Of the 428 women who met inclusion criteria, 81.8% had a BMI of 40-50, 14.5% had a BMI of 50-60, and 3.7% had a BMI higher than 60. The overall cesarean delivery rate was 49.1% (46% with BMI 40-50, 63% with BMI 50-60, and 69% with BMI higher than 60, P=.012). Of the 428 women studied, 77.6% were black and 55% were nulliparous. Nulliparity, height, initial cervical dilation, and modified Bishop score were associated with a higher rate of cesarean delivery in multivariable models. Maternal and neonatal composite morbidity was higher in obese women who underwent cesarean delivery, compared with those who delivered vaginally. The performance of a previously developed induction calculator applied to this cohort had an area under the ROC curve of 75% (95% CI 0.70-0.79).

CONCLUSIONS

In women with class III obesity who underwent labor induction, the cesarean delivery rate approaches 50%. Nulliparity, height, and unfavorable cervical examination were the most significant risk factors for cesarean delivery. This information can be used to augment counseling for the obese patient who is undergoing induction.

Guideline No. 392-Pregnancy and Maternal Obesity Part 2: Team Planning for Delivery and Postpartum Care

OBJECTIVE

This guideline will review key aspects in the pregnancy care of women with obesity. Part I will focus on Preconception and Pregnancy Care. Part II will focus on Team Planning for Delivery and Postpartum Care.

INTENDED USERS

All health care providers (obstetricians, family doctors, midwives, nurses, anaesthesiologists) who provide pregnancy-related care to women with obesity.

TARGET POPULATION

Women with obesity who are pregnant or planning pregnancies.

EVIDENCE

Literature was retrieved through searches of Statistics Canada, Medline, and The Cochrane Library on the impact of obesity in pregnancy on antepartum and intrapartum care, maternal morbidity and mortality, obstetric anaesthesia, and perinatal morbidity and mortality. Results were restricted to systematic reviews, randomized controlled trials/controlled clinical trials, and observational studies. There were no date or language restrictions. Searches were updated on a regular basis and incorporated in the guideline to September 2018. Grey (unpublished) literature was identified through searching the websites of health technology assessment and health technology assessment-related agencies, clinical practice guideline collections, clinical trial registries, and national and international medical specialty societies.

VALIDATION METHODS

The content and recommendations were drafted and agreed upon by the authors. Then the Maternal-Fetal Medicine Committees peer reviewed the content and submitted comments for consideration, and the Board of the Society of Obstetricians and Gynaecologists of Canada (SOGC) approved the final draft for publication. Areas of disagreement were discussed during meetings at which time consensus was reached. The level of evidence and quality of the recommendation made were described using the Evaluation of Evidence criteria of the Canadian Task Force on Preventive Health Care.

BENEFITS, HARMS, AND COSTS

Implementation of the recommendations in these guidelines may increase obstetrical provider recognition of the issues affecting pregnant individuals with obesity, including clinical prevention strategies, communication between the health care team, the patient and family as well as equipment and human resource planning. It is hoped that regional, provincial and federal agencies will assist in the education and support of coordinated care for pregnant individuals with obesity.

GUIDELINE UPDATE

SOGC guideline will be automatically reviewed 5 years after publication. However, authors can propose another review date if they feel that 5 years is too short/long based on their expert knowledge of the subject matter.

SPONSORS

This guideline was developed with resources funded by the SOGC.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Outcomes of Elective Induction of Labor versus Expectant Management among Obese Women at ≥39 Weeks

OBJECTIVE

Maternal obesity is associated with many adverse obstetric outcomes including cesarean delivery. It is unclear whether induction of labor can reduce these risks. Previous studies report conflicting results on the outcomes of elective induction of labor among obese women. This study aimed to compare maternal and neonatal outcomes between obese women undergoing elective induction of labor and those undergoing expectant management at ≥39 weeks.

STUDY DESIGN

This was a retrospective cohort study from the Consortium on Safe Labor of obese women (defined by prepregnancy body mass index≥ 30kg/m²) with singleton gestations at ≥39 weeks without medical comorbidities from 2002 through 2008. Women scheduled for medically indicated induction of labor were excluded. The primary outcome of cesarean delivery was compared between obese women undergoing elective induction of labor and expectant management during 39th, 40th, and 41st weeks using univariable and multivariable analyses, stratifying by parity.

RESULTS

In all, 7,298 nulliparous and 9,789 parous women were eligible for analysis. After controlling for potential confounders, elective induction of labor during 39th week in nulliparous and parous women was associated with lower odds of cesarean delivery (39.1 vs. 41.6%, adjusted odds ratio [OR]: 0.47, 95% confidence interval [CI]: 0.30-0.74 for nulliparous and 5.5 vs. 10.1%, adjusted OR: 0.34, 95% CI: 0.20-0.61 for parous women) compared with expectant management. Elective induction of labor during 40th and 41st weeks was not associated with lower odds of cesarean delivery. In addition, macrosomia was reduced in nulliparous women undergoing elective induction of labor during the 40th week (12.1 vs. 18.5%, adjusted OR: 0.56, 95% CI: 0.35-0.87) and in parous women undergoing elective induction of labor during 39th (11.6 vs. 17.6%, adjusted OR: 0.50, 95% CI: 0.38-0.66) and 40th weeks (16.4 vs. 22.2%, adjusted OR: 0.53, 95% CI: 0.36-0.78).

CONCLUSION

Elective induction of labor at 39 weeks, when compared with expectant management, was associated with lower cesarean deliveries in obese nulliparous and parous women.

A systematic scoping review of clinical indications for induction of labour

BACKGROUND

The proportion of women undergoing induction of labour (IOL) has risen in recent decades, with significant variation within countries and between hospitals. The aim of this study was to review research supporting indications for IOL and determine which indications are supported by evidence and where knowledge gaps exist.

METHODS

A systematic scoping review of quantitative studies of common indications for IOL. For each indication, we included systematic reviews/meta-analyses, randomised controlled trials (RCTs), cohort studies and case control studies that compared maternal and neonatal outcomes for different modes or timing of birth. Studies were identified via the databases PubMed, Maternity and Infant Care, CINAHL, EMBASE, and ClinicalTrials.gov from between April 2008 and November 2019, and also from reference lists of included studies. We identified 2554 abstracts and reviewed 300 full text articles. The quality of included studies was assessed using the RoB 2.0, the ROBINS-I and the ROBIN tool.

RESULTS

68 studies were included which related to post-term pregnancy (15), hypertension/pre-eclampsia (15), diabetes (9), prelabour rupture of membranes (5), twin pregnancy (5), suspected fetal compromise (4), maternal elevated body mass index (BMI) (4), intrahepatic cholestasis of pregnancy (3), suspected macrosomia (3), fetal gastroschisis (2), maternal age (2), and maternal cardiac disease (1). Available evidence supports IOL for women with post-term pregnancy, although the evidence is weak regarding the timing (41 versus 42 weeks), and for women with hypertension/preeclampsia in terms of improved maternal outcomes. For women with preterm premature rupture of membranes (24-37 weeks), high-quality evidence supports expectant management rather than IOL/early birth. Evidence is weakly supportive for IOL in women with term rupture of membranes. For all other indications, there were conflicting findings and/or insufficient power to provide definitive evidence.

CONCLUSIONS

While for some indications, IOL is clearly recommended, a number of common indications for IOL do not have strong supporting evidence. Overall, few RCTs have evaluated the various indications for IOL. For conditions where clinical equipoise regarding timing of birth may still exist, such as suspected macrosomia and elevated BMI, researchers and funding agencies should prioritise studies of sufficient power that can provide quality evidence to guide care in these situations.

Directive clinique No 392 - Grossesse et obésité maternelle Partie 2 : Planification en équipe de l'accouchement et soins post-partum

OBJECTIF

La présente directive clinique aborde les aspects essentiels des soins prénataux chez les femmes atteintes d'obésité. La partie 1 porte sur la préconception et les soins prénataux. La partie 2 porte sur la planification en équipe de l'accouchement et les soins post-partum. UTILISATEURS CONCERNéS: Tous les fournisseurs de soins de santé (obstétriciens, médecins de famille, sages-femmes, infirmières, anesthésiologistes) qui prodiguent des soins relatifs à la grossesse auprès de femmes atteintes d'obésité.

POPULATION CIBLE

Femmes atteintes d'obésité qui sont enceintes ou prévoient le devenir. DONNéES PROBANTES: Des recherches ont été menées en consultant les ressources de Statistique Canada, de Medline et de Cochrane Library en vue d'en tirer la littérature relativement aux effets de l'obésité durant la grossesse sur les soins prénataux et intrapartum, la morbidité et la mortalité maternelles, l'anesthésie obstétricale ainsi que sur la morbidité et la mortalité périnatales. Seuls les résultats de revues systématiques, d'essais cliniques randomisés ou comparatifs et d'études observationnelles ont été retenus. Aucune restriction de date ou de langue n'a été employée. Les recherches ont été mises à jour régulièrement, et les résultats ont été incorporés à la directive clinique jusqu'en septembre 2018. Nous avons également tenu compte de la littérature grise (non publiée) obtenue sur les sites Web d'organismes d'évaluation des technologies de la santé et d'autres organismes pertinents, dans des collections de directives cliniques et des registres d'essais cliniques, et auprès d'associations nationales et internationales de médecins spécialistes. MéTHODES DE VALIDATION: Le contenu et les recommandations ont été rédigés et acceptés par les auteurs. Les membres du comité de médecine fœto-maternelle ont ensuite passé en revue le contenu et formulé des commentaires aux fins d'examen. Enfin, le conseil d'administration de la Société des obstétriciens et gynécologues du Canada (SOGC) a approuvé la publication de la version définitive de la directive. Les points de désaccord ont été abordés lors de réunions pour enfin arriver à un consensus. La qualité des données et des recommandations a été déterminée à l'aide des critères d'évaluation décrits par le Groupe d'étude canadien sur les soins de santé préventifs. AVANTAGES, PRéJUDICE ET COûTS: La mise en place des recommandations des présentes directives peut améliorer la reconnaissance des fournisseurs de soins obstétricaux relativement aux problèmes qui touchent les personnes enceintes atteintes d'obésité, notamment au moyen de stratégies de prévention clinique; de la communication entre l'équipe de soins de santé, la patiente et la famille; et de la planification de l'équipement et des ressources humaines. Il est à espérer que les organismes régionaux, provinciaux et fédéraux participeront à la formation et au soutien en matière de soins coordonnés pour les personnes enceintes atteintes d'obésité. MISE à JOUR DE LA DIRECTIVE CLINIQUE: Les directives de la SOGC sont automatiquement passées en revue 5 ans après leur publication. Les auteurs peuvent toutefois proposer une autre date de réévaluation s'ils croient qu'une période de 5 ans est trop courte ou trop longue en fonction de leurs connaissances du sujet à titre d'experts en la matière.

PROMOTEURS

La présente directive a été élaborée à l'aide de ressources financées par la SOGC. DéCLARATIONS SOMMAIRES: RECOMMANDATIONS.

Elective induction of labor at 39 weeks compared with expectant management: a meta-analysis of cohort studies

BACKGROUND

Elective induction of labor at 39 weeks among low-risk nulliparous women has reduced the chance of cesarean and other adverse maternal and perinatal outcomes in a randomized trial, although its clinical effectiveness in nonresearch settings remains uncertain.

OBJECTIVE

To perform a systematic review of observational studies that compared elective induction of labor at 39 weeks among nulliparous women with expectant management and to use meta-analytic techniques to estimate the association of elective induction with cesarean delivery, as well as other maternal and perinatal outcomes.

STUDY DESIGN

Studies were eligible for this meta-analysis only if they: (1) were observational; (2) compared women undergoing labor induction at 39 weeks with women undergoing expectant management beyond that gestational age; (3) included women in the induction group only if they had no other indication for labor induction at 39 weeks; and (4) provided data specifically for nulliparous women. The predefined primary outcome was cesarean delivery, and secondary outcomes representing other maternal and perinatal morbidities also were evaluated. Outcome data from different studies were combined to estimate pooled relative risks with 95% confidence intervals using random-effects models.

RESULTS

Of 375 studies identified by the initial search, 6 cohort studies, which included 66,019 women undergoing elective labor induction at 39 weeks and 584,390 undergoing expectant management, met inclusion criteria. Elective induction of labor at 39 weeks was associated with a significantly lower frequency of cesarean delivery (26.4% vs 29.1%; relative risk, 0.83; 95% confidence interval, 0.74-0.93), as well as of peripartum infection (2.8% vs 5.2%; relative risk, 0.53; 95% confidence interval, 0.39-0.72). Neonates of women in the induction group were less likely to have respiratory morbidity (0.7% vs 1.5%; relative risk, 0.71; 95% confidence interval, 0.59-0.85); meconium aspiration syndrome (0.7% vs 3.0%; relative risk, 0.49; 95% confidence interval, 0.26-0.92); and neonatal intensive care unit admission (3.5% vs 5.5%; relative risk, 0.80; 95% confidence interval, 0.72-0.88). There also was a lower risk of perinatal mortality (0.04% vs 0.2%; relative risk, 0.27; 95% confidence interval, 0.09-0.76).

CONCLUSION

This meta-analysis of 6 cohort studies demonstrates that elective induction of labor at 39 weeks, compared with expectant management beyond that gestational age, was associated with a significantly lower risk of cesarean delivery, maternal peripartum infection, and perinatal adverse outcomes, including respiratory morbidity, intensive care unit admission, and mortality.

Induction of labour indications and timing: A systematic analysis of clinical guidelines

BACKGROUND

There is widespread and some unexplained variation in induction of labour rates between hospitals. Some practice variation may stem from variability in clinical guidelines. This review aimed to identify to what extent induction of labour guidelines provide consistent recommendations in relation to reasons for, and timing of, induction of labour and ascertain whether inconsistencies can be explained by variability guideline quality.

METHOD

We conducted a systematic search of national and international English-language guidelines published between 2008 and 2018. General induction of labour guidelines and condition-specific guidelines containing induction of labour recommendations were searched. Guidelines were reviewed and extracted independently by two reviewers. Guideline quality was assessed using the Appraisal of Guidelines for Research and Evaluation II Instrument.

FINDINGS

Forty nine guidelines of varying quality were included. Indications where guidelines had mostly consistent advice included prolonged pregnancy (induction between 41 and 42 weeks), preterm premature rupture of membranes, and term preeclampsia (induction when preeclampsia diagnosed ≥37 weeks). Guidelines were also consistent in agreeing on decreased fetal movements and oligohydramnios as valid indications for induction, although timing recommendations were absent or inconsistent. Common indications where there was little consensus on validity and/or timing of induction included gestational diabetes, fetal macrosomia, elevated maternal body mass index, and twin pregnancy.

CONCLUSION

Substantial variation in clinical practice guidelines for indications for induction exists. As guidelines rated of similar quality presented conflicting recommendations, guideline variability was not explained by guideline quality. Guideline variability may partly account for unexplained variation in induction of labour rates.

Is vaginal misoprostol more effective than oral misoprostol for cervical ripening in obese women?

Objective: To determine if vaginal misoprostol is more effective than oral misoprostol for cervical ripening in obese women.Study design: A retrospective cohort study of obese women undergoing induction of labor from Jan 2013 to Dec 2016 with singleton, viable pregnancies beyond 37 completed weeks of gestational age. Women with an initial Bishop score of 7 or less, with a cervical dilatation of less than 2 cm, who received either vaginal or oral misoprostol as a cervical ripening agent, were included. Primary outcome was interval from the start of induction to the attainment of 3 cm cervical dilatation. Secondary outcomes included the interval from the start of induction to delivery and the rate of cesarean delivery (CD).Result: Of women who met the inclusion criteria, 966 (75.5%) women received oral misoprostol and 314 (24.5%) received vaginal misoprostol. The mean time-interval from the start of induction to attainment of 3-cm dilatation was shorter in the vaginal group (10.5 ± 10.4 h) compared to the oral group (17.2 ± 11.5 h), (p < .0001). Significantly shorter times to delivery were also noted in the vaginal group (17.4 h for vaginal vs. 24.8 h for oral, p < .0001). In the subgroup analysis of nulliparous women, shorter time intervals from the start of induction to attainment of 3-cm dilatation, as well as to delivery, were noted in the vaginal misoprostol group (p < .0001 for both). Multiple linear regression model confirmed route of misoprostol administration as an independent variable in predicting the outcomes (time from start of induction to 3 cm as well as to delivery). Significant findings amongst neonatal outcomes included lower umbilical artery pH and higher rates of neonatal jaundice in the oral misoprostol group.Conclusion: In a population of obese women undergoing induction of labor, vaginal administration of misoprostol was associated shorter time intervals from the start of induction to the attainment of 3 cm of dilatation, as well as to delivery, without increasing the rate of cesarean deliveries or the incidence of adverse maternal and neonatal outcomes.

Contraction of the levator ani muscle during Valsalva maneuver (coactivation) is associated with a longer active second stage of labor in nulliparous women undergoing induction of labor

BACKGROUND

The Valsalva maneuver is normally accompanied by relaxation of the levator ani muscle, which stretches around the presenting part, but in some women the maneuver is accompanied by levator ani muscle contraction, which is referred to as levator ani muscle coactivation. The effect of such coactivation on labor outcome in women undergoing induction of labor has not been previously assessed.

OBJECTIVE

The aim of the study was to assess the effect of levator ani muscle coactivation on labor outcome, in particular on the duration of the second and active second stage of labor, in nulliparous women undergoing induction of labor.

STUDY DESIGN

Transperineal ultrasound was used to measure the anteroposterior diameter of the levator hiatus, both at rest and at maximum Valsalva maneuver, in a group of nulliparous women undergoing induction of labor in 2 tertiary-level university hospitals. The correlation between anteroposterior diameter of the levator hiatus values and levator ani muscle coactivation with the mode of delivery and various labor durations was assessed.

RESULTS

In total, 138 women were included in the analysis. Larger anteroposterior diameter of the levator hiatus at Valsalva was associated with a shorter second stage (r = -0.230, P = .021) and active second stage (r = -0.338, P = .001) of labor. Women with levator ani muscle coactivation had a significantly longer active second stage duration (60 ± 56 vs 28 ± 16 minutes, P < .001). Cox regression analysis, adjusted for maternal age and epidural analgesia, demonstrated an independent significant correlation between levator ani muscle coactivation and a longer active second stage of labor (hazard ratio, 2.085; 95% confidence interval, 1.158-3.752; P = .014). There was no significant difference between women who underwent operative delivery (n = 46) when compared with the spontaneous vaginal delivery group (n = 92) as regards anteroposterior diameter of the levator hiatus at rest and at Valsalva maneuver, nor in the prevalence of levator ani muscle coactivation (10/46 vs 15/92; P = .49).

CONCLUSION

Levator ani coactivation is associated with a longer active second stage of labor.

A conceptual framework for the impact of obesity on risk of cesarean delivery

Cesarean deliveries accounted for 32.2% of nearly 4 million births in the United States in 2014. Obesity affects a third of reproductive-age women and is associated with worse cesarean delivery outcomes. Studies have shown that increasing maternal body mass index correlates linearly with cesarean delivery rates, but little is known about the potential mediating and moderating mechanisms. Thus, a conceptual framework for understanding how obesity correlates with risk of cesarean delivery is crucial to determining safe ways to reduce the cesarean delivery rate among obese gravidas. Based on an extensive review and synthesis of the literature, we present a conceptual framework that posits how obesity may operate through several pathways to lead to a cesarean delivery. Our framework explores the complexity of obesity as an exposure that operates through potential mediating pathways, a moderator of cesarean delivery risk, and a covariate with other cesarean delivery risk factors. Among nulliparas, obesity appears to operate through 3 main proximal mediating mechanisms to increase risk of cesarean delivery including: (1) preexisting comorbidities and obstetric complications; (2) a slower progression of first-stage labor, potentially increasing the risk of cesarean delivery secondary to failure to progress; and (3) a prolongation of pregnancy, which is associated with risk of maternal postdates. For multiparas, a fourth proximal mediator of prior uterine scar may also increase cesarean delivery risk. Distal mediating mechanisms, which operate through one of the proximal mechanisms, may include an induction of labor or planned prelabor cesarean delivery. Obesity may also moderate the likelihood of cesarean delivery by interacting with clinician-level or hospital-level factors. Future research should assess the validity of this framework and seek to understand the relative contributions of each potential pathway between obesity and cesarean delivery. This will allow for evidence-based recommendations to reduce preventable cesareans among obese women by targeting modifiable mediators and moderators of the relationship between obesity and increased risk of cesarean delivery.

Labor Induction versus Expectant Management in Low-Risk Nulliparous Women

BACKGROUND

The perinatal and maternal consequences of induction of labor at 39 weeks among low-risk nulliparous women are uncertain.

METHODS

In this multicenter trial, we randomly assigned low-risk nulliparous women who were at 38 weeks 0 days to 38 weeks 6 days of gestation to labor induction at 39 weeks 0 days to 39 weeks 4 days or to expectant management. The primary outcome was a composite of perinatal death or severe neonatal complications; the principal secondary outcome was cesarean delivery.

RESULTS

A total of 3062 women were assigned to labor induction, and 3044 were assigned to expectant management. The primary outcome occurred in 4.3% of neonates in the induction group and in 5.4% in the expectant-management group (relative risk, 0.80; 95% confidence interval [CI], 0.64 to 1.00). The frequency of cesarean delivery was significantly lower in the induction group than in the expectant-management group (18.6% vs. 22.2%; relative risk, 0.84; 95% CI, 0.76 to 0.93).

CONCLUSIONS

Induction of labor at 39 weeks in low-risk nulliparous women did not result in a significantly lower frequency of a composite adverse perinatal outcome, but it did result in a significantly lower frequency of cesarean delivery. (Funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development; ARRIVE ClinicalTrials.gov number, NCT01990612 .).