Induction of labor in the obese patient

Methods of induction of labor in women with obesity: A secondary analysis of two multicenter randomized controlled trials

INTRODUCTION

Obesity is an increasing public health concern worldwide and can lead to more complications in pregnancy and childbirth. Women with obesity more often require induction of labor for various indications. The aim of this study is to assess which method of induction of labor is safest and most effective in women with obesity.

MATERIAL AND METHODS

This is a secondary analysis of two randomized controlled trials about induction of labor. Women with a term singleton pregnancy in cephalic presentation, an unfavorable cervix, intact membranes and without a previous cesarean section were randomly allocated to cervical priming with a Foley catheter or vaginal prostaglandin-E2-gel (PROBAAT-I) or a Foley catheter or oral misoprostol (PROBAAT-II). The inclusion and exclusion criteria for the studies were identical. Induction methods were compared in women with obesity (body mass index ≥30.0). Main outcomes were cesarean section and postpartum hemorrhage (blood loss >1000 mL).

RESULTS

A total of 2664 women, were included in the trials, 517 of whom were obese: 254 women with obesity received a Foley catheter, 176 oral misoprostol and 87 prostaglandin E2 (PGE2). A cesarean section was performed in 29.1% of women allocated to Foley vs 22.2% in the misoprostol and 23.0% in the PGE2 groups. Comparisons between groups revealed no statistically significant differences: the relative risk [RR] was 1.31 (95% confidence interval [CI] 0.94-1.84) in the Foley vs misoprostol group and 1.27 (95% CI 0.83-1.95) in the Foley vs PGE2 group. The rates of postpartum hemorrhage were comparable (10.6%, 11.4% and 6.9%, respectively; P = 0.512). In women with obesity, more often a switch to another method occurred in the Foley group, (20.1% vs 6.3% in misoprostol vs 1.1% in the PGE2 group; P < 0.001). The risk of a failed Foley placement was higher in women with obesity than in women without obesity (8.3% vs 3.2%; adjusted odds ratio 3.12, 95% CI 1.65-5.90).

CONCLUSIONS

In women with obesity we found a nonsignificant trend towards an increased rate of cesarean sections in the group induced with a Foley catheter compared to oral misoprostol; however, the study lacked power for this subgroup analysis. The finding of a higher risk of failed placement of a Foley catheter in women with obesity can be used in shared decision making.

Prediction of successful labor induction with very unfavorable cervix: A comparison of six scores

OBJECTIVE

To compare the ability of six scoring systems to predict successful labor induction with cervical ripening among women with a Bishop score <3.

METHODS

Secondary analysis of data from a prospective, multicenter observational Methods of Induction of Labor and Perinatal Outcomes (MEDIP) cohort study in 94 obstetrical French units. We included women with a Bishop score <3 before cervical ripening. We compared six scores: Bishop, simplified Bishop, modified Bishop, simplified Bishop including parity, Hughey, and Levine scores. Vaginal delivery defined successful labor induction. The ability of each score to predict successful labor induction was evaluated by comparing their area under the curve (AUC).

RESULTS

Among the 600 eligible women in this study, 408 (68%) delivered vaginally. Body mass index (calculated as weight in kilograms divided by the square of height in meters; mean ± standard deviation [SD]: 24.7 ± 5.5 vs 26.0 ± 5.7; P = 0.01) and nulliparity (48.8% vs 85.4%; P < 0.001) were lower in the successful induction group, whereas height was higher (mean ± SD: 165.3 ± 6.0 cm vs 163.7 ± 6.0 cm; P = 0.002). The simplified Bishop including parity, Hughey, and Levine scores had the highest AUC (0.70, 95% confidence interval [CI] 0.65-0.73; 0.68, 95% CI 0.64-0.74; and 0.69, 95% CI 0.65-0.74, respectively).

CONCLUSION

In women with a very unfavorable cervix, scores that include parity predict successful labor induction more accurately, such as simplified Bishop including parity, Hughey, or Levine scores.

Comparison of the effectiveness and pregnancy outcomes of labor induction with dinoprostone or single-balloon catheter in term nulliparous women with borderline oligohydramnios

BACKGROUNDS

At present, there is no consensus on the induction methods in term pregnancy with borderline oligohydramnios. This study aimed to compare the effectiveness and pregnancy outcomes of labor induction with dinoprostone or single-balloon catheter (SBC) in term nulliparous women with borderline oligohydramnios.

METHODS

We conducted a retrospective cohort study from January 2016 to November 2018. During the study period, a total of 244 cases were enrolled. Of these, 103 cases were selected for induction using dinoprostone and 141 cases were selected for induction with SBC. The pregnancy outcomes between the two groups were compared. Primary outcomes were successful vaginal delivery rates. Secondary outcomes were maternal and neonatal adverse events. Multivariate logistic regression was used to assess the risk factors for vaginal delivery failure in the two groups.

RESULTS

The successful vaginal delivery rates were similar between the dinoprostone group and the SBC group (64.1% [66/103] vs. 59.6%, [84/141] P = 0.475), even after adjustment for potential confounding factors (adjusted odds ratio [aOR]: 1.07, 95% confidence interval [CI]: 0.57-2.00, P = 0.835). The incidence of intra-amniotic infection was lower in the dinoprostone group than in the SBC group (1.9% [2/103] vs. 7.8%, [11/141] P < 0.001), but the presence of non-reassuring fetal heart rate was higher in the dinoprostone group than in the SBC group (12.6% [13/103] vs. 0.7%, [1/141] P < 0.001). Multivariate logistic regression showed that nuchal cord was a risk factor for vaginal delivery failure after induction with dinoprostone (aOR: 6.71, 95% CI: 1.96-22.95). There were three factors related to vaginal delivery failure after induction with SBC, namely gestational age (aOR: 1.51, 95% CI: 1.07-2.14), body mass index (BMI) >30 kg/m2 (aOR: 2.98, 95% CI: 1.10-8.02), and fetal weight >3500 g (aOR: 2.49, 95% CI: 1.12-5.50).

CONCLUSIONS

Term nulliparous women with borderline oligohydramnios have similar successful vaginal delivery rates after induction with dinoprostone or SBC, with their advantages and disadvantages. In women with nuchal cord, the risk of vaginal delivery failure is increased if dinoprostone is used in the induction of labor. BMI >30 kg/m2, large gestational age, and estimated fetal weight >3500 g are risk factors for vaginal delivery failure after induction with SBC.

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..

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.

Women's body mass index and oral administration of Misoprostol for induction of labor - A retrospective cohort study

Pregnant women who are obese are at greater risk of pregnancy complications, including preeclampsia, gestational diabetes, and macrosomia, leading to an increased likelihood of induced labor. Little is known about pregnant women with obesity and the dose of Misoprostol needed for induction of labor (IOL). To investigate whether the cumulative dose of Misoprostol needed for induction of labor (IOL) is associated with women's body mass index (BMI), we conducted a retrospective study of the use of oral Misoprostol for IOL at the Department of Obstetrics and Gynecology, Aarhus University Hospital - a tertiary referral delivery unit with 4800 deliveries a year. Data on IOL among 1637 women with singleton pregnancies was collected in the period January 1st, 2014, to October 4th, 2017. Low-risk women were induced in an outpatient setting. Primary outcomes were Misoprostol dose, time between start of induction (first dose of Angusta®) and completed delivery, and mode of delivery. Secondary outcomes were neonatal data as Apgar score and pH of the umbilical artery. In this study, we found the total dose of Misoprostol needed for induction increased significantly with increasing BMI (p < 0.005). The time to delivery and the risk of Cesarean section increased with rising BMI class. However, 76% of inductions among the women with obesity ended in a vaginal delivery. For the neonatal outcomes, a total of 16 children had an Apgar score below 7 at five minutes and 14 had a pH less than 7.0; none of these results differed significantly between BMI classes. The perinatal and maternal mortality rate was 0%.

The Myometrium in Pregnant Women with Obesity

Obesity is a worldwide public health problem, affecting at least one-third of pregnant women. One of the main problems of obesity during pregnancy is the resulting high rate of cesarean section. The leading cause of this higher frequency of cesarean sections in obese women, compared with that in nonobese women, is an altered myometrial function that leads to lower frequency and potency of contractions. In this article, the disruptions of myometrial myocytes were reviewed in obese women during pregnancy that may explain the dysfunctional labor. The myometrium of obese women exhibited lower expression of connexin43, a lower function of the oxytocin receptor, and higher activity of the potassium channels. Adipokines, such as leptin, visfatin, and apelin, whose concentrations are higher in obese women, decreased myometrial contractility, perhaps by inhibiting the myometrial RhoA/ROCK pathway. The characteristically higher cholesterol levels of obese women alter myometrial myocyte cell membranes, especially the caveolae, inhibiting oxytocin receptor function, and increasing the K+ channel activity. All these changes in the myometrial cells or their environment decrease myometrial contractility, at least partially explaining the higher rate of cesarean of sections in obese women.

Use of the Robson classification to understand the increased risk of cesarean section in case of maternal obesity

BACKGROUND

The aim of this study was to identify characteristics of pregnant women with obesity that contribute to increased cesarean rate.

METHODS

Retrospective cohort in a single academic institution between 2012 and 2019. Women who delivered during this period were classified according to the Robson classification. Women with normal body mass index (N = 11,797) and with obesity (N = 2991) were compared. The contribution of each Robson group to the overall caesarean rate were compared.

RESULTS

The overall cesarean rate was higher for women with (28.1%) than without (14.2%, p < 0.001) obesity. This result came mainly from Robson group 5a (history of one cesarean). After adjustment for medical factors within this group, the association between maternal obesity and cesarean during labor was significant.

CONCLUSIONS

The higher cesarean rate in women with obesity is explained by Robson group 5a in which obesity is an independent risk factor of in labor cesarean delivery.

Risk factors for failed induction of labor among pregnant women with Class III obesity

INTRODUCTION

Our aim was to identify risk factors for failed induction in morbidly obese patients undergoing the induction of labor at term.

MATERIAL AND METHODS

This was a retrospective multicenter study on a cohort of 235 patients with a body mass index greater than 40 kg/m² and giving birth to a singleton in cephalic presentation, who had an induction of labor from 38 weeks of amenorrhea. Scheduled cesareans and spontaneous vaginal deliveries were excluded. Maternal, peri-partum and neonatal characteristics were analyzed according to the delivery route.

RESULTS

In all, 235 patients were included. Of these, 62.5% patients delivered vaginally and 37.5% by cesarean section. The frequency of nulliparity was greater in patients who had a cesarean section (56 [interquartile range, IQR, 38.1] vs 56 [IQR 63.6], P < .001). In multivariate analysis, nulliparity (odds ratio [OR] 2.81, 95% confidence interval [CI] 1.58-4.97], P < .001), low Bishop's score (OR .794, 95% CI .70-.90, P < .001) and weight gain (OR 1.04, 95% CI 1.01-1.08, P = .033) were independent risk factors for failed induction. Umbilical cord pH at birth lower than 7 (0 vs 7 [IQR 8.0], P < .001) and lower than 7.20 (36 [IQR 24.5] vs 35 [IQR 39.8], P = .014) as well as the Apgar at 1 minute (14 [IQR 9.5] vs 17 [IQR 19.3], P = .032) was significantly higher in infants born by cesarean section.

CONCLUSIONS

In this cohort, 63% of women with Class III obesity had successful inductions of labor; risk factors for failed induction include nulliparity and unfavorable Bishop score.

Balloon catheter vs oxytocin alone for induction of labor in women with a previous cesarean section: A randomized controlled trial

INTRODUCTION

The aim of this study was to compare the efficacy and maternal-neonatal morbidity between balloon catheter and oxytocin for induction of labor in women with a previous cesarean section and an unfavorable cervix.

MATERIAL AND METHODS

This open-label randomized controlled trial took place in seven French hospitals. Inclusion criteria were medical indication for labor induction in pregnant women, ≥37 weeks, with lower segment cesarean section, Bishop score ≤4, no pre-labor rupture of membranes, singleton fetus in cephalic presentation. Women were allocated randomly to induction with a 50-mL balloon catheter for 12 hours or a low-dose oxytocin infusion. Primary outcome was the rate of vaginal birth. Secondary outcomes were maternal and neonatal complications.

RESULTS

The study enrolled 204 women from 26 December 2010 to 31 December 2013: 101 were allocated to receive balloon catheter and 103 to oxytocin. Vaginal birth rate was 50% (n = 51) in the balloon catheter group vs 37% (n = 38) in the oxytocin group (P = 0.050). Maternal and neonatal morbidity did not differ between balloon catheter and oxytocin groups: two uterine dehiscences vs one, one vs four maternal infections, five vs two hemorrhages and 11 vs five neonatal transfers, respectively. Heterogeneity of treatment effect for vaginal delivery was observed across initial Bishop scores. Balloon catheter was more effective for low values of bishop score.

CONCLUSIONS

Balloon catheter tended to be associated with a higher probability of vaginal delivery as compared with low-dose intravenous oxytocin when used for induction of labor in women with a previous cesarean section and low Bishop score at induction.

Labor induction with misoprostol vaginal insert compared with dinoprostone vaginal insert

INTRODUCTION

Misoprostol vaginal insert could lead to a significant reduction in the time to vaginal delivery, and an increase in the proportion of women achieving vaginal delivery, compared with dinoprostone vaginal insert. We compared the delivery outcomes of misoprostol 200 μg vaginal insert and dinoprostone 10 mg vaginal insert for induction of labor in women with an unfavorable cervix.

MATERIAL AND METHODS

This is a retrospective observational study conducted on a cohort of 220 women with a Bishop score ≤4 admitted for induction of labor at a single institution. Of these, 109 (49.5%) received the misoprostol vaginal insert and 111 (50.5%) received the dinoprostone vaginal insert. The primary outcome was the vaginal delivery rate. Secondary outcomes were time from induction to vaginal delivery, time to any delivery mode, time from induction to the onset of active labor, oxytocin use, uterine tachysystole and need for tocolysis.

RESULTS

The vaginal delivery rate was 88% in the misoprostol insert group, compared with 74% in the dinoprostone insert group (P < 0.007). The average time from drug administration to the beginning of labor was shorter in the misoprostol compared with the dinoprostone group (855 min vs 1740 min, P < 0.0001). Also, the average time from administration to delivery was shorter for women receiving misoprostol compared with dinoprostone (1113 min vs 2150 min, P < 0.0001). The use of misoprostol reduced the need for oxytocin compared with dinoprostone (30.2% vs 43.2%, P = 0.046). Finally, compared with dinoprostone, the misoprostol insert was associated with more uterine tachysystole (38% vs 12%, P < 0.001), but the rate of tachysystole requiring tocolysis was not significantly different between the 2 groups (51.2% vs 46.1%, P = 0.1). Multivariate analysis showed that Bishop score and method of induction, but not maternal body mass index or gestational age at induction, were independently associated with mode of delivery.

CONCLUSIONS

The cesarean section rate was significantly lower in the misoprostol insert group. The use of misoprostol was also associated with reduced time to vaginal delivery and time to onset of active labor and with decreased use of oxytocin. Tachysystole was a frequent complication during induction of labor with the misoprostol insert.

A comparison of cervical ripening modalities among overweight and obese nulliparous gravidas

Objective: To determine if differences exist among nulliparous overweight and obese gravidas undergoing cervical ripening employing three different agents (dinoprostone, misoprostol, or cervical catheter).Methods: A retrospective cohort study of nulliparous overweight and obese women who underwent induction of labor at two south-central Pennsylvania hospitals between January 2014 and December 2017. Nulliparous gravidas, ≥37 weeks' gestational age, with singleton pregnancies in the vertex presentation, were included in the study. We employed the following definitions: (1) overweight: BMI 25.0-29.9 kg/m²; (2) class I obesity: BMI 30.0-34.9 kg/m²; (3) class II obesity: BMI 35.0-39.9 kg/m²; and (4) class III obesity: BMI >40.0 kg/m². The primary outcome measure was the mean difference in induction-to-birth time. A subanalysis was performed to assess the effect of BMI on the primary outcome. Secondary outcome measures included mode of delivery, induction-to-second-stage-of-labor time, estimated blood loss, neonatal feeding type, neonatal Apgar scores, and neonatal admission to triage or intensive care unit (ICU) after delivery. A priori power calculation estimated that 156 patients would be needed using the medium effective size. Data analysis was performed using ANOVA for continuous variables and chi-square tests for categorical variables.Results: Among 192 nulliparous overweight and obese gravidas, 70 received dinoprostone, 72 were given misoprostol, and 50 had cervical ripening with cervical catheters. There were no significant differences in mean induction to birth times among overweight and obese women when comparing the three cervical ripening agents (dinoprostone 24.5 ± 15.2 versus misoprostol 28.7 ± 12.3 and catheters 25.1 ± 12.9 hours), (p = .145, 95% CI -8.7 to 0.2 and -5.5 to 4.3, respectively). Overweight nulliparous women had shorter mean induction to birth time (22.9 ± 11.4 versus 29.2 ± 15.8 hours) as compared to class II obese women, (p = .037, 95% CI -12.0 to -0.38). When overweight women were compared to class III obese women, shorter mean induction to birth time (22.9 ± 11.4 versus 30.9 ± 13.9 hours) was also found, (p = .005, 95% CI -13.4 to -2.4).Conclusion: Among nulliparous overweight and obese gravidas, neither dinoprostone, misoprostol, or cervical catheter significantly impacted the induction to birth time. There was a longer induction to birth time for class II and class III obese women when compared to overweight women. Additional studies are warranted to improve cervical ripening in nulliparous overweight and obese women.

Influence of maternal obesity on Bishop Score and failed induction of labour: A retrospective cohort study in a regional tertiary centre

BACKGROUND

Maternal obesity is a growing health concern that has previously been associated with increased need for induction of labour (IOL) and caesarean section (CS) rates. Currently, limited evidence explores the influence of maternal body mass index (BMI) on Bishop Score (BS) and outcome of IOL. This study hypothesises that maternal obesity will lead to a lower BS at presentation, higher rates of failed IOL, and increased CS rates.

AIMS

To explore the influence of maternal obesity on BS and likelihood of failed IOL.

METHODS

A retrospective cohort analysis was conducted of all live, term, singleton, cephalic deliveries initiated with IOL across normal BMI (18.00-24.99), overweight BMI (25.00-29.99), and obese BMI (>30.00) at the Townsville Hospital and Health Service (THHS) between July 2011 to June 2016. Student's t-test, χ² test, and binary logistic regression were used for statistical analysis. BS and failed IOL, defined as CS with cervical dilatation <3 cm, were the primary outcome measures. Delivery mode was the secondary outcome measure.

RESULTS

A total of 1543 women were included, 678 with normal BMI, 370 with overweight BMI, and 495 with obese BMI. Obese women are more likely to have a low BS (<5) at presentation (unadjusted odds ratio (OR) 1.5 (1.1-2.0), P < 0.05), an increased rate of failed IOL (adjusted OR (aOR) 1.6 (1.0-2.5), P < 0.05) and increased CS rate (aOR 1.1 (1.0-1.9), P < 0.05), compared to normal weight women.

CONCLUSIONS

Maternal obesity is associated with a lower BS, more difficult IOL process, and increased risk of failed IOL and CS.