Term induction of labor and subsequent preterm birth

The association between induction of labour in nulliparous women at term and subsequent spontaneous preterm birth: a retrospective cohort study

OBJECTIVES

To evaluate the rate of subsequent spontaneous preterm birth in patients with previous induction of labour at term compared to women with previous spontaneous labour at term.

METHODS

This was a retrospective cohort study of all women with consecutive births at the Royal Brisbane and Women's Hospital between 2014 and 2018. All nulliparous women with a singleton pregnancy and induction of labour at term or in spontaneous labour at term in the index pregnancy were included. Data was extracted from electronic medical records. The outcome of spontaneous preterm birth in the subsequent pregnancy was compared between patients with previous term induction of labour and in previous term spontaneous labour.

RESULTS

A total of 907 patients with consecutive births met the inclusion criteria; of which 269 (29.7%) had a term induction of labour and 638 (70.3%) had a term spontaneous labour in the index pregnancy. The overall subsequent spontaneous preterm birth rate was 2.3%. Nulliparous women who underwent term induction of labour were less likely to have a subsequent preterm birth compared to nulliparous women in term spontaneous labour (0.74 vs. 2.98%; odds ratio [OR], 0.25; 95% confidence interval, 0.06-1.07; p=0.0496) in the index pregnancy. This however was not significant once adjusted for confounders (adjusted OR, 0.29; p=0.10). Spontaneous preterm birth was associated with a previous spontaneous labour compared to induction of labour between 37 to 37⁺⁶ and 38 to 38⁺⁶ weeks (adjusted OR 0.18 and 0.21; p=0.02 and 0.004 respectively).

CONCLUSIONS

Term induction of labour does not increase the risk of subsequent spontaneous preterm birth compared to spontaneous labour at term in nulliparous women. Further research is needed to validate these findings in a larger cohort of women and to evaluate the effect of elective IOL among low-risk nulliparous women.

Risk of preterm delivery after medically indicated termination of pregnancy with induced vaginal delivery: a case-control study

We investigated whether nonsurgical termination of pregnancy after 14 weeks of gestation increases the risk of preterm delivery in a subsequent pregnancy. We conducted a two-centre retrospective case-control study. Patients who underwent non-surgical termination of pregnancy after 14 weeks of gestation between 2012 and 2015 and who gave birth after 14 weeks of gestation to a live-born singleton infant were included. Control patients were those who gave birth after 37 weeks of gestation (the same month as a case patient) and had a second delivery of a singleton foetus after 14 weeks of gestation. The primary outcome was preterm delivery during the second pregnancy period. We included 151 cases and 302 controls and observed 13 (8.6%) preterm births during the second pregnancy in the case group versus 8 (2.6%) (odds ratio: 3.62; 95% confidence interval: 1.40-8.65, p < .001) in the control group. This result remained significant after multivariate analysis. Impact statementWhat is already known about this topic? Many studies have evaluated the association between first-trimester surgical or non-surgical termination of pregnancy and the risk of preterm birth in the subsequent pregnancy. However, no study has evaluated the association between second- or third-trimester non-surgical termination of pregnancy due to foetal disease and the risk of preterm birth in the subsequent pregnancy. A small number of studies have included a small proportion of patients who previously underwent non-surgical termination of pregnancy after 14 weeks of gestation and later experienced first-trimester termination during their second pregnancy. These studies focussed on the impact of the interpregnancy interval or pharmacological induction of labour on the risk of preterm delivery in the subsequent pregnancy.What did the results of this study add? This is the first study to specifically evaluate the association between second- and third-trimester non-surgical terminations of pregnancy and the risk of preterm birth in the subsequent pregnancy. When compared with term birth, nonsurgical termination of pregnancy was associated with the risk of spontaneous preterm birth and hospitalisation in the neonatal intensive care unit in the subsequent pregnancy.What are the implications of these findings for clinical practice and further research? Further studies are required to confirm our results, but information delivered to patients with a late termination of pregnancy and during their pregnancy follow-up for the subsequent pregnancy could be modified to provide this information.

Duration of the second stage of labour and risk of subsequent spontaneous preterm birth

OBJECTIVES

To determine the risk of spontaneous preterm birth (sPTB) associated with the length of second stage of labour in the first term delivery.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

POPULATION

Women with first two consecutive singleton births and the first birth at term. Those who did not reach the second stage of labour in the first delivery were excluded.

METHODS

Charts from 2007 to 2019 were reviewed.

MAIN OUTCOME MEASURES

Rate of sPTB (<37 weeks of gestation) in the second delivery.

RESULTS

Of 13 958 women who met study inclusion criteria, 1464 (10.5%) parturients had a prolonged second stage (≥180 min) in their first term delivery. The rate of sPTB in the second delivery was similar in those with and without a prolonged second stage in first delivery (2.8% versus 2.8%; adjusted odds ratio [aOR] 1.35, 95% CI 0.96-1.90). After adjustment for mode of delivery, prolonged second stage was also not associated with subsequent sPTB in those who delivered by spontaneous and operative vaginal delivery. Those delivered by second-stage caesarean section in the first delivery had a higher risk of sPTB in the second delivery (25/526, 4.8%; aOR 2.66, 95% CI 1.71-4.12; p < 0.001), with a more pronounced risk in those with second-stage caesarean following a prolonged second stage of labour (15/259, 5.8%; aOR 3.40, 95% CI 1.94-5.94; p < 0.001).

CONCLUSION

Second-stage duration in a first term vaginal delivery is not associated with subsequent sPTB. The risk of sPTB is increased following second-stage caesarean section, particularly if performed after a prolonged second stage.

Induction of labor with Foley catheter and risk of subsequent preterm birth: follow-up study of two randomized controlled trials (PROBAAT-1 and -2)

OBJECTIVE

To evaluate the rate of preterm birth (PTB) in a subsequent pregnancy in women who had undergone term induction using a Foley catheter compared with prostaglandins.

METHODS

This was a follow-up study of two large randomized controlled trials (PROBAAT-1 and PROBAAT-2). In the original trials, women with a term singleton pregnancy with the fetus in cephalic presentation and with an indication for labor induction were randomized to receive either a 30-mL Foley catheter or prostaglandins (vaginal prostaglandin E2 in PROBAAT-1 and oral misoprostol in PROBAAT-2). Data on subsequent ongoing pregnancies > 16 weeks' gestation were collected from hospital charts from clinics participating in this follow-up study. The main outcome measure was preterm birth < 37 weeks' gestation in a subsequent pregnancy.

RESULTS

Fourteen hospitals agreed to participate in this follow-up study. Of the 1142 eligible women, 572 had been allocated to induction of labor using a Foley catheter and 570 to induction of labor using prostaglandins. Of these, 162 (14%) were lost to follow-up. In total, 251 and 258 women had a known subsequent pregnancy > 16 weeks' gestation in the Foley catheter and prostaglandin groups, respectively. There were no differences in baseline characteristics between the groups. The overall rate of PTB in a subsequent pregnancy was 9/251 (3.6%) in the Foley catheter group vs 10/258 (3.9%) in the prostaglandin group (relative risk (RR), 0.93; 95% CI, 0.38-2.24), and the rate of spontaneous PTB was 5/251 (2.0%) vs 5/258 (1.9%) (RR, 1.03; 95% CI, 0.30-3.51).

CONCLUSION

In women with term singleton pregnancy, induction of labor using a 30-mL Foley catheter is not associated with an increased risk of PTB in a subsequent pregnancy, as compared to induction of labor using prostaglandins. © 2020 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

The Risk of Preterm Birth in Women with Three Consecutive Deliveries-The Effect of Number and Type of Prior Preterm Births

Background: We aimed to explore the association of the number, order, gestational age and type of prior PTB and the risk of preterm birth (PTB) in the third delivery in women who had three consecutive singleton deliveries. Methods: A retrospective cohort study of all women who had three consecutive singleton births at a single medical center over a 20-year period (1994-2013). The primary outcome was PTB (<37 weeks) in the third delivery. Results: 4472 women met inclusion criteria. The rate of PTB in the third delivery was 4.9%. In the adjusted analysis, the risk of PTB was 3.5% in women with no prior PTBs; 10.9% in women with prior one PTB only in the first pregnancy; 16.2% in women with prior one PTB only in the second pregnancy; and 56.5% in women with prior two PTBs. A similar trend was observed when the outcome of interest was spontaneous PTB and when the exposure was limited to prior spontaneous or indicated PTB. Conclusions: In women with a history of PTB, the risk of recurrent PTB in subsequent pregnancies is related to the number and order of prior PTBs. These factors should be taken into account when stratifying the risk of PTB.

Risk of preterm birth after prior term cesarean

Objective

To determine the risk of overall preterm birth (PTB) and spontaneous PTB in a pregnancy after a caesarean section (CS) at term.

Design

Longitudinal linked national cohort study.

Setting

The Dutch Perinatal Registry (1999–2009).

Population

268 495 women with two subsequent singleton pregnancies were identified.

Methods

A cohort study based on linked registered data from two subsequent pregnancies in the Netherlands.

Main outcome measures

The incidence of overall PTB and spontaneous PTB with subgroup analysis on gestational age at first delivery and type of CS (planned or unplanned).

Results

Of 268 495 women with a singleton first pregnancy who delivered at term, 15.76% (n = 42 328) had a CS. The incidence of PTB in the second pregnancy was 2.79% (n = 1182) in women with a previous CS versus 2.46% (n = 5570) in women with a previous vaginal delivery (adjusted odds ratio [aOR] 1.14, 95% confidence interval [CI] 1.07–1.21). This increased risk is mainly driven by an increased risk of spontaneous PTB after previous CS at term (aOR 1.50, 95% CI 1.38–1.70). Analysis for type of CS compared with vaginal delivery showed an aOR on spontaneous PTB of 1.86 (95% CI 1.58–2.18) for planned CS and an aOR of 1.40 (95% CI 1.24–1.58) for unplanned CS.

Conclusions

CS at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Tweetable abstract

Caesarean section at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Caesarean section at term is associated with a marginally increased risk of spontaneous PTB in a subsequent pregnancy.

Comparison of Clinical Characteristics and Outcomes of Peripartum Cardiomyopathy Between African American and Non-African American Women

Importance

Peripartum cardiomyopathy (PPCM) disproportionately affects women of African ancestry, but well-powered studies to explore differences in severity of disease and clinical outcomes are lacking.

Objective

To compare the clinical characteristics, presentation, and outcomes of PPCM between African American and non-African American women.

Design, Setting, and Participants

This retrospective cohort study using data from January 1, 1986, through December 31, 2016, performed at the University of Pennsylvania Health System, a tertiary referral center serving a population with a high proportion of African American individuals, included 220 women with PPCM.

Main Outcomes and Measures

Demographic and clinical characteristics and echocardiographic findings at presentation, as well as clinical outcomes including cardiac recovery, time to recovery, cardiac transplant, persistent dysfunction, and death, were compared between African American and non-African American women with PPCM.

Results

A total of 220 women were studied (mean [SD] age at diagnosis, 29.5 [6.6] years). African American women were diagnosed with PPCM at a younger age (27.6 vs 31.7 years, P < .001), were diagnosed with PPCM later in the postpartum period, and were more likely to present with a left ventricular ejection fraction less than 30% compared with non-African American women (48 [56.5%] vs 30 [39.5%], P = .03). African American women were also more likely to worsen after initial diagnosis (30 [35.3%] vs 14 [18.4%], P = .02), were twice as likely to fail to recover (52 [43.0%] vs 24 [24.2%], P = .004), and, when they did recover, recovery took at least twice as long (median, 265 vs 125.5 days; P = .02) despite apparent adequate treatment.

Conclusions and Relevance

In a large cohort of women with well-phenotyped PPCM, this study demonstrates a different profile of disease in African American vs non-African American women. Further work is needed to understand to what extent these differences stem from genetic or socioeconomic differences and how treatment of African American patients might be tailored to improve health outcomes.

Interpregnancy Body Mass Index Changes: Distribution and Impact on Adverse Pregnancy Outcomes in the Subsequent Pregnancy

OBJECTIVE

To examine the change in body mass index (BMI) categories between pregnancies and its effect on adverse pregnancy outcomes.

STUDY DESIGN

We performed a retrospective cohort study of women with two consecutive deliveries from 2005 to 2010. Analysis was limited to women with BMI recorded at <24 weeks for both pregnancies. Standard BMI categories were used. Adverse pregnancy outcomes included preterm birth at <37 weeks, intrauterine growth restriction (IUGR), pregnancy-related hypertension, and gestational diabetes mellitus (GDM). Women with increased BMI category between pregnancies were compared with those who remained in the same BMI category.

RESULTS

In total, 537 women were included, of whom 125 (23%) increased BMI category. There was no association between increase in BMI category and risk of preterm birth, IUGR, or pregnancy-related hypertension. Women who increased BMI category had an increased odds of GDM compared with women who remained in the same BMI category (6.4 vs. 2.2%; p = 0.018). The increased risk remained after controlling for age, history of GDM, and starting BMI (adjusted odds ratio: 8.2; 95% confidence interval: 2.1-32.7; p = 0.003).

CONCLUSION

Almost one-quarter of women increased BMI categories between pregnancies. This modifiable risk factor has a significant impact on the risk of GDM.

The Effect of Prior Term Birth on Risk of Recurrent Spontaneous Preterm Birth

OBJECTIVE

 The objective of this study was to evaluate the effect of prior term birth on recurrent spontaneous preterm birth (sPTB) risk.

STUDY DESIGN

 Retrospective cohort study of 211 women with prior sPTB, comparing women with and without prior term births. The primary outcome was recurrent sPTB <37 weeks. Analyses stratified by gestational age of prior sPTB and adjusted for confounders using multivariable logistic regression.

RESULTS

 The overall sPTB rate was 33.7%, with no statistical difference between women with and without prior term births (28.9 vs. 37.7%, p = 0.2). Among women with prior second-trimester loss (16-23^6/7 weeks), those with a term birth had a decreased sPTB rate (15.4 vs. 43.2%, p = 0.02), which persisted after adjusting for age and 17-α hydroxyprogesterone caproate use. For women with prior sPTB ≥24 weeks, there was no difference in sPTB with and without prior term births (29.5 vs. 26.6%, p = 0.7). A term birth as the most recent delivery lowered, but did not eliminate, the sPTB risk (19.1 vs. 36.4%, p = 0.1).

CONCLUSION

 Prior term birth lowers the risk of recurrent sPTB for women with prior second-trimester loss, but not for women with prior sPTB ≥24 weeks. Women with prior preterm and term births should be counseled accordingly and all sPTB prevention strategies should be recommended.

Length of second stage of labor and preterm birth in a subsequent pregnancy

BACKGROUND

During the second stage of labor, it is plausible that the pressure of the fetal head against a completely dilated cervix may lead to changes in the cervical integrity and cervical strength lending it susceptible to premature dilation in a subsequent pregnancy. Therefore, a prolonged second stage of labor has been hypothesized to be a risk factor for cervical insufficiency and spontaneous preterm birth (sPTB).

OBJECTIVE

We sought to evaluate the effect that the length of second stage of labor in one pregnancy has on the risk of sPTB in a subsequent pregnancy.

STUDY DESIGN

This was a planned secondary analysis of a large retrospective cohort study of women with 2 consecutive deliveries at our institution from 2005 through 2010. Women with a term pregnancy that reached the second stage were included; women with a prior sPTB were excluded. The primary outcome was sPTB <37 weeks. A prolonged second stage was defined as ≥3 hours. Fisher exact tests were used to compare categorical data. Linear and logistic regression was used to calculate odds.

RESULTS

In all, 757 women were included. The overall length of the second stage ranged from 0-7.3 hours. The sPTB rate in a subsequent pregnancy was 8.7%. There was no association between length of second stage (hours) as a continuous variable and sPTB after adjusting for confounders (adjusted odds ratio, 0.83; [95% CI 0.58-1.20]). A prolonged second stage ≥3 hours occurred in 48 (6.3%) women. Women with a second stage ≥3 hours were older, less likely to be African American, and were less likely to be overweight or obese as compared to women with a second stage <3 hours. The women with second stage ≥3 hours were more likely to be nulliparous and have a larger neonate. The sPTB risk was not different between a second stage ≥3 hours (10.4%) and <3 hours (7.9%), P = .5. The sPTB risk was, however, modified by mode of delivery in the second stage. There was no difference in sPTB rate among women with a vaginal delivery when comparing those with and without a prolonged second stage (7.4 vs 7.8%, P = .9). There also was no difference among women with a cesarean when comparing those with and without a prolonged second stage (11.8 vs 14.3%, P = .8). While not statistically significant, the absolute risk of a subsequent sPTB after a cesarean delivery with a second stage ≥3 hours is twice as high as the risk of a sPTB after a vaginal delivery with a second stage ≥3 hours (adjusted odds ratio, 2.08; [0.32-13.78]).

CONCLUSION

A prolonged second stage of labor alone does not increase the risk of sPTB in a subsequent pregnancy. Cesarean delivery after a prolonged second stage of labor may confer a possible increased risk. It is important to continue to evaluate potential risk factors for sPTB. If these risk factors are confirmed in future studies, it will aid in the counseling of women and may open the door for therapeutic strategies to be studied among these newly identified at-risk women.

Cervical ripening with the balloon catheter and the risk of subsequent preterm birth

OBJECTIVE

To examine the risk of subsequent preterm birth after cervical ripening using a balloon catheter.

STUDY DESIGN

A retrospective study was held at a university teaching hospital between January 2007 and June 2013. The study group included women who underwent cervical ripening using a balloon (single or double) catheter in the previous pregnancy followed by a subsequent singleton delivery (balloon catheter group). Two control groups were included. The first was similar to the study group except that ripening was achieved in the previous pregnancy with vaginal prostaglandin E2 (PGE2 group). The second control group had a previous pregnancy that resulted in spontaneous onset of labor at term (unexposed group). The primary outcome was the incidence of spontaneous preterm birth (before 37 weeks) in the index pregnancy.

RESULT

Overall, 558 women were included; each group consisted of 186 women. The incidence of spontaneous preterm birth in the index pregnancy did not differ between the groups (0.5, 1.6 and 2.7% in the balloon catheter, PGE2 and in the unexposed groups, respectively, P=0.31). Among the balloon catheter group, 58 (31.2%) women had the ripening performed with a single-balloon catheter and 128 (68.8%) women with a double-balloon catheter. The rate of the spontaneous preterm birth in the index pregnancy did not differ between the two groups (P=1.0).

CONCLUSION

Cervical ripening with a balloon catheter does not increase the rate of subsequent spontaneous preterm birth.

The utility of ICD9-CM codes in identifying induction of labor

BACKGROUND

Data evaluating the accuracy of ICD9-CM codes in identifying inductions are limited. Our objective was to examine the test characteristics of ICD9-CM coding for induction of labor and to identify differences between those captured by coding and those not.

METHODS

We performed a retrospective cohort study of ICD9-CM codes in identifying charts of induced women at our institution from 2005 to 2009. Review of the medical record was the gold standard. Characteristics of the charts were compared using Mann-Whitney U tests and chi-square tests where appropriate.

RESULTS

A total of 3,263 women were included, 708 with ICD9-CM coding for induction (screen positive). A total of 422 women were randomly sampled from those not coded as induction (screen negative). The sensitivity of ICD9-CM coding for induction was 51.4%, specificity 98.8%, positive predictive value 96.6%, negative predictive value 74.7%. False negative charts (25%) were more likely to be women induced for premature rupture of membranes (40% versus 8%, p < 0.001) or with oxytocin (51% versus 33%, p < 0.001) when compared with screen positive charts.

CONCLUSIONS

It is reassuring that 97% of charts coded for induction by ICD9-CM codes are, in fact, patients that were induced. With this degree of accuracy, we can be confident that charts coded as induction are unlikely to be miscoded.

Does stage of labor at time of cesarean delivery affect risk of subsequent preterm birth?

OBJECTIVE

The effect of a cesarean delivery in different stages of labor on spontaneous preterm birth (sPTB) in a subsequent pregnancy has not been studied extensively. The objective of the study was to evaluate the risk of subsequent sPTB after a first-stage or second-stage cesarean delivery compared with a vaginal delivery.

STUDY DESIGN

This was a planned secondary analysis of a large retrospective cohort study of women with 2 consecutive deliveries from 2005-2010. Women with a previous sPTB were excluded. First-stage (<10 cm) and second-stage (≥10 cm) cesarean deliveries were compared with vaginal deliveries. Data were obtained through chart abstraction. The primary outcome was sPTB (<37 wk) in a subsequent pregnancy. Categoric variables were compared with the use of χ(2) analyses, and logistic regression was used to calculate odds and control for confounders.

RESULTS

Eight hundred eighty-seven women were included (721 vaginal deliveries; 129 first-stage and 37 second-stage cesarean deliveries). The sPTB rate varied between groups (7.8%, 2.3%, and 13.5%, respectively; P = .03). When compared with women with a vaginal delivery, women with a first-stage cesarean delivery had a decreased risk of sPTB, which remained after adjustment for confounders (adjusted odds ratio, 0.30; 95% confidence interval, 0.09-0.99; P = .049). There was a nonsignificant increase in odds of sPTB after a second-stage cesarean delivery compared with a vaginal delivery (adjusted odds ratio, 2.4; 95% confidence interval, 0.77-7.43; P = .13). Women with a second-stage cesarean delivery had a 6-fold higher odds of sPTB compared with women with a first-stage cesarean delivery, which remained after adjustment for confounders (adjusted odds ratio, 5.8; 95% confidence interval, 1.08-30.8; P = .04).

CONCLUSION

Women with a full-term second-stage cesarean delivery have a significantly higher than expected rate of subsequent sPTB (13.5%) compared with both the overall national sPTB rate (7-8%) and to a first-stage cesarean delivery (2.3%). As the cesarean delivery rate continues to rise, this potential impact on pregnancy outcomes cannot be ignored.

Labor length among overweight and obese women undergoing induction of labor

OBJECTIVE

Maternal weight is thought to impact labor. With rising rates of obesity and inductions, we sought to evaluate labor times among induced women by body mass index (BMI) category.

METHODS

Retrospective cohort study of term inductions from 2005 to 2010. BMI categories were: normal weight (NW), overweight (OW), and obese (Ob) (18.5-24.9, 25-29.9, ≥30 kg/m(2)). Kruskal-Wallis tests compared median latent labor (LL) length and active labor (AL) length. Chi-square determined associations. Multivariable logistic regression controlled for confounders. Analyses were stratified by parity.

RESULTS

A total of 448 inductions were analyzed. For nulliparas, there was no difference in LL by BMI category (p = 0.22). However, OW nulliparas had a longer AL compared to NW and Ob nulliparas (3.2, 1.7, 2.0 h, p = 0.005). For multiparas, NW had the shortest LL (5.5 h, p = 0.025) with no difference in AL among BMI categories (p = 0.42). The overall cesarean rate was 23% with no difference by BMI category (p = 0.95). However, Ob women had a greater percentage of first stage cesareans (41%) and NW had a greater percentage of second stage cesareans (55%), p = 0.06.

CONCLUSION

The association between BMI and labor length among inductions differs by phase of labor and parity. BMI also influences the stage of labor in which a cesarean occurs.

Term induction of labor and risk of cesarean delivery by parity

OBJECTIVE

To evaluate the risk of cesarean delivery among both nulliparous and multiparous women undergoing a term induction of labor compared to women that present in spontaneous labor at term.

METHODS

We performed a retrospective cohort study of term (≥37 weeks) singleton pregnancies between 2005 and 2010 comparing women that had an induction to those that presented in spontaneous labor. Multiparity was defined as a prior delivery after 20 weeks' gestation. Chi-square was used to compare categorical variables. Multivariable logistic regression was used to control for confounders. Analyses were stratified by parity.

RESULTS

863 women were included in the analysis. There were 605 inductions (cesarean rate 23%) and 257 spontaneous labor (cesarean rate 7%), OR 3.4, 95% CI [2.1-5.4]. Stratified by parity, nulliparas undergoing induction had an increased cesarean rate compared to spontaneous labor (27% versus 11%, OR 3.13, 95% CI [1.76-5.57]) as did multiparas (13% versus 3%, OR 4.04, 95% CI [1.36-11.94]). This increased risk for cesarean after induction remained in both nulliparous and multiparous women even after controlling for confounders (aOR 2.90, 95% CI [1.60-5.25] and aOR 3.47, 95% CI [1.12-10.67], respectively). Neither starting cervical exam nor indication for induction altered this increased risk.

CONCLUSIONS

The increased risk of cesarean in women undergoing an induction is present regardless of parity and indication for induction. This should be taken into account when counseling women regarding risks of induction, regardless of parity. Future studies should focus on other clinical characteristics of induction that may mitigate this risk.