The active management of risk in multiparous pregnancy at term: association between a higher preventive labor induction rate and improved birth outcomes

Outcomes among Nulliparous Women Undergoing Nonmedically Indicated Induction of Labor at 39 Weeks Compared with Expectant Management Differ by Maternal Age

OBJECTIVE

 Prior studies have demonstrated the potential benefit of nonmedically indicated induction of labor for nulliparous women at 39 weeks of gestation, yet few have studied the impact of this management strategy in different maternal age groups on obstetric outcomes. We sought to assess whether obstetric outcomes among women undergoing nonmedically indicated induction of labor at 39 weeks of gestation as compared with expectant management vary based on maternal age.

STUDY DESIGN

 This was a retrospective cohort study of singleton, nonanomalous, deliveries between 2007 and 2012 in California. We defined nonmedically indicated induction of labor as induction of labor without a specific medical indication, and women with planned cesarean sections were excluded. We compared induction of labor with expectant management beyond the gestational age of induction and examined this comparison in different maternal age groups. Numerous maternal and neonatal outcomes were examined. Chi-squared and multivariable logistic regression analyses were used for statistical comparisons and a p-value of less than 0.05 was used to indicate statistical significance.

RESULTS

 A total of 630,485 women-infant dyads met our inclusion criteria and were included in this study. At 39 weeks' gestation, 6% of women underwent nonmedically indicated induction of labor and 94% underwent expectant management. Women 20 to 34 and ≥35 years old had lower odds of cesarean delivery if they underwent induction of labor. Women of all ages undergoing nonmedically indicated induction of labor had higher odds of operative vaginal delivery. Neonatal outcomes were better with nonmedically indicated induction of labor, including lower odds of neonatal intensive care unit admission and neonatal respiratory distress.

CONCLUSION

 Our study demonstrated that obstetric outcomes vary among women undergoing nonmedically indicated induction of labor compared with expectant management when stratified by maternal age. These findings illustrate the importance of understanding age-related differences in outcomes associated with nonmedically indicated induction of labor.

KEY POINTS

· Outcomes are different by age with nonmedically indicated induction of labor (IOL).. · The odds of cesarean delivery with IOL decreases with increasing maternal age compared with expectant management.. · Neonatal outcomes were improved with IOL compared with 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..

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.

Definition of Failed Induction of Labor and Its Predictive Factors: Two Unsolved Issues of an Everyday Clinical Situation

OBJECTIVE

The objectives of this review were to identify the predictive factors of induction of labor (IOL) failure or success as well as to highlight the current heterogeneity regarding the definition and diagnosis of failed IOL.

MATERIALS AND METHODS

Only studies in which the main or secondary outcome was failed IOL, defined as not entering the active phase of labor after 24 h of prostaglandin administration ± 12 h of oxytocin infusion, were included in the review. The data collected were: study design, definition of failed IOL, induction method, IOL indications, failed IOL rate, cesarean section because of failed IOL and predictors of failed IOL.

RESULTS

The database search detected 507 publications. The main reason for exclusion was that the primary or secondary outcomes were not the predetermined definition of failed IOL (not achieving active phase of labor). Finally, 7 studies were eligible. The main predictive factors identified in the review were cervical status, evaluated by the Bishop score or cervical length.

DISCUSSION

Failed IOL should be defined as the inability to achieve the active phase of labor, considering that the definition of IOL is to enter the active phase of labor. A universal definition of failed IOL is an essential requisite to analyze and obtain solid results and conclusions on this issue. An important finding of this review is that only 7 of all the studies reviewed assessed achieving the active phase of labor as a primary or secondary IOL outcome. Another conclusion is that cervical status remains the most important predictor of IOL outcome, although the value of the parameters explored up to now is limited. To find or develop predictive tools to identify those women exposed to IOL who may not reach the active phase of labor is crucial to minimize the risks and costs associated with IOL failure while opening a great opportunity for investigation. Therefore, other predictive tools should be studied in order to improve IOL outcome in terms of health and economic burden.

Risk factors for cesarean delivery following labor induction in multiparous women

OBJECTIVE

To identify potential risk factors for cesarean delivery following labor induction in multiparous women at term.

METHODS

We conducted a retrospective case-control study. Cases were parous women in whom the induction of labor had resulted in a cesarean delivery. For each case, we used the data of two successful inductions as controls. Successful induction was defined as a vaginal delivery after the induction of labor. The study was limited to term singleton pregnancies with a child in cephalic position.

RESULTS

Between 1995 and 2010, labor was induced in 2548 parous women, of whom 80 had a cesarean delivery (3%). These 80 cases were compared to the data of 160 parous women with a successful induction of labor. In the multivariate analysis history of preterm delivery (odds ratio (OR) 5.3 (95% CI 1.1 to 25)), maternal height (OR 0.87 (95% CI 0.80 to 0.95)) and dilatation at the start of induction (OR 0.43 (95% CI 0.19 to 0.98)) were associated with failed induction.

CONCLUSION

In multiparous women, the risk of cesarean delivery following labor induction increases with previous preterm delivery, short maternal height, and limited dilatation at the start of induction.

The influence of hospital type on induction of labor and mode of delivery

OBJECTIVE

The purpose of this study was to compare labor induction and cesarean delivery rates at term in community vs university hospitals.

STUDY DESIGN

A population-based retrospective cohort study of births was performed. Primary outcomes were term gestation at <39 weeks, labor induction, and cesarean delivery. After we adjusted for comorbidities, malpresentation, and previous cesarean delivery, logistic regression assessed the association between hospital type and primary outcomes.

RESULTS

Births occur less often in week 37 (n = 24390 [11%] vs 4006 [13%]; adjusted odds ratio [OR], 0.9; 95% confidence interval [CI], 0.8-0.9) and are similar in week 38 in community vs university hospitals. Inductions occur more commonly in community vs university settings at 37 weeks (n = 6440 [27%] vs 757 [19%]; adjusted OR, 1.7; 95% CI, 1.5-1.8) and at 38 weeks (n = 16586 [31%] vs 1530 [21%]; adjusted OR, 1.8; 95% CI, 1.7-1.9). Cesarean rates are no different between hospital types.

CONCLUSION

Induction is 70-80% more likely at community vs university hospitals before the optimal gestational age of ≥ 39 weeks, but cesarean delivery rates do not differ at term.

What's new in obstetric anesthesia?

The current article covers some of the major themes that emerged in 2009 in the fields of obstetric anesthesiology, obstetrics, and perinatology, with a special emphasis on the implications for the obstetric anesthesiologist.