Term cesarean delivery in the first pregnancy is not associated with an increased risk for preterm delivery in the subsequent pregnancy.

Prior studies have reported an increased risk for preterm delivery following a term cesarean delivery. However, these studies did not adjust for high-risk conditions related to the first cesarean delivery and are known to recur. The objective of the study was to determine whether there is an association between term cesarean delivery in the first pregnancy and subsequent spontaneous or indicated preterm delivery. This was a retrospective cohort study of women with the first 2 consecutive singleton deliveries (2007-2014) identified through a linked pregnancy database at a single institution. Women with a first pregnancy that resulted in cesarean delivery at term were compared with women whose first pregnancy resulted in a vaginal delivery at term. Exclusion criteria were known to recur medical or obstetrical complications during the first pregnancy. A propensity score analysis was performed by matching women who underwent a cesarean delivery with those who underwent a vaginal delivery in the first pregnancy. The association between cesarean delivery in the first pregnancy and preterm delivery in the second pregnancy in this matched set was examined using conditional logistic regression. The primary outcome was overall preterm delivery <37 weeks in the second pregnancy. Secondary outcomes included type of preterm delivery (spontaneous vs indicated), late preterm delivery (34-36 6/7 weeks), early preterm delivery (<34 weeks), and small-for-gestational-age birth. Of a total of 6456 linked pregnancies, 2284 deliveries were matched; 1142 were preceded by cesarean delivery and 1142 were preceded by vaginal delivery. The main indications for cesarean delivery in the first pregnancy were dystocia in 703 (61.5%), nonreassuring fetal status in 222 (19.4%), breech presentation in 100 (8.8%), and other in 84 (7.4%). The mean (SD) gestational ages at delivery for the second pregnancy was 38.8 (1.8) and 38.9 (1.7) weeks, respectively, for prior cesarean delivery and vaginal delivery. The risks of preterm delivery in the second pregnancy among women with a previous cesarean and vaginal delivery were 6.0% and 5.2%, respectively (adjusted odds ratio, 1.46, 95% confidence interval, [CI] 0.77-2.76). In an analysis stratified by the type of preterm delivery in the second pregnancy, no associations were seen between cesarean delivery in the first pregnancy and spontaneous preterm delivery (4.6% vs 3.9%; adjusted odds ratio, 1.40, 95% confidence interval, 0.59-3.32) or indicated preterm delivery (1.6% vs 1.4%; adjusted odds ratio, 1.21, 95% confidence interval, 0.60-2.46). Similarly, no significant differences were found in late preterm delivery (4.6% vs 4.1%; adjusted odds ratio, 1.13, 95% confidence interval, 0.55-2.29), early preterm delivery (1.6% vs 1.2%; adjusted odds ratio, 1.25, 95% confidence interval, 0.59-2.67), or neonates with birthweight less than the fifth percentile for gestational age (3.6% vs 2.2%; adjusted odds ratio, 1.26, 95% confidence interval, 0.52-3.06). After robust adjustment for confounders through a propensity score analysis related to the indication for the first cesarean delivery at term, cesarean delivery is not associated with an increase in preterm delivery, spontaneous or indicated, in the subsequent pregnancy.

Vahanian SA ，Hoffman MK ，Ananth CV ，Croft DJ ，Duzyj C ，Fuchs KM ，Gyamfi-Bannerman C ，Kinzler WL ，Plante LA ，Ranzini AC ，Rosen TJ ，Skupski DW ，Smulian JC ，Vintzileos AM ，Perinatal Research Consortium ... -  《-》

Maternal and newborn outcomes with elective induction of labor at term.

A growing body of evidence supports improved or not worsened birth outcomes with nonmedically indicated induction of labor at 39 weeks gestation compared with expectant management. This evidence includes 2 recent randomized control trials. However, concern has been raised as to whether these studies are applicable to a broader US pregnant population. Our goal was to compare outcomes for electively induced births at ≥39 weeks gestation with those that were not electively induced. We conducted a retrospective cohort study using chart-abstracted data on births from January 1, 2012, to December 31, 2017, at 21 hospitals in the Northwest United States. The study was restricted to singleton cephalic hospital births at 39+0-42+6 weeks gestation. Exclusions included previous cesarean birth, missing data for delivery type or gestational week at birth, antepartum stillbirth, cesarean birth without any attempt at vaginal birth, fetal anomaly, gestational diabetes mellitus, prepregnancy diabetes mellitus, and prepregnancy hypertension. The rate of cesarean birth for elective inductions at both 39 and 40 weeks gestation was compared with the rate in all other on-going pregnancies in the same gestational week. Maternal outcomes (operative vaginal birth, shoulder dystocia, 3rd- or 4th-degree perineal laceration, pregnancy-related hypertension, and postpartum hemorrhage) and newborn infant outcomes (macrosomia, 5-minute Apgar <7, resuscitation at delivery, intubation, respiratory complications, and neonatal intensive care unit admission) were also compared between elective inductions and on-going pregnancies at 39 and 40 weeks gestation. Logistic regression modeling was used to produce odds ratios for outcomes with adjustment for maternal age and body mass index. Results were stratified by parity and gestational week at birth. Duration of hospital stay (admission to delivery, delivery to discharge, and total stay) were compared between elective inductions and on-going pregnancies. A total of 55,694 births were included in the study cohort: 4002 elective inductions at ≥39+0 weeks gestation and 51,692 births at 39+0-42+6 weeks gestation that were not electively induced. In nulliparous women, elective induction at 39 weeks gestation was associated with a decreased likelihood of cesarean birth (14.7% vs 23.2%; adjusted odds ratio, 0.61; 95% confidence interval, 0.41-0.89) and an increased rate of operative vaginal birth (18.5% vs 10.8%; adjusted odds ratio, 1.8; 95% confidence interval, 1.28-2.54) compared with on-going pregnancies. In multiparous women, cesarean birth rates were similar in the elective inductions and on-going pregnancies. Elective induction at 39 weeks gestation was associated with a decreased likelihood of pregnancy-related hypertension in nulliparous (2.2% vs 7.3%; adjusted odds ratio, 0.28; 95% confidence interval, 0.11-0.68) and multiparous women (0.9% vs 3.5%; adjusted odds ratio, 0.24; 95% confidence interval, 0.15-0.38). Term elective induction was not associated with any statistically significant increase in adverse newborn infant outcomes. Elective induction of labor at 39 weeks gestation was associated with increased time from admission to delivery for both nulliparous (1.3 hours; 95% confidence interval, 0.2-2.3) and multiparous women (3.4 hours; 95% confidence interval, 3.2-3.6). Elective induction of labor at 39 weeks gestation is associated with a decrease in cesarean birth in nulliparous women, decreased pregnancy-related hypertension in multiparous and nulliparous women, and increased time in labor and delivery. How to use this information remains the challenge.

Souter V ，Painter I ，Sitcov K ，Caughey AB ... -  《-》

Early preterm preeclampsia outcomes by intended mode of delivery.

The optimal route of delivery in early-onset preeclampsia before 34 weeks is debated because many clinicians are reluctant to proceed with induction for perceived high risk of failure. Our objective was to investigate labor induction success rates and compare maternal and neonatal outcomes by intended mode of delivery in women with early preterm preeclampsia. We identified 914 singleton pregnancies with preeclampsia in the Consortium on Safe Labor study for analysis who delivered between 24 0/7 and 33 6/7 weeks. We excluded fetal anomalies, antepartum stillbirth, or spontaneous preterm labor. Maternal and neonatal outcomes were compared between women undergoing induction of labor (n = 460) and planned cesarean delivery (n = 454) and women with successful induction of labor (n = 214) and unsuccessful induction of labor (n = 246). We calculated relative risks and 95% confidence intervals to determine outcomes by Poisson regression model with propensity score adjustment. The calculation of propensity scores considered covariates such as maternal age, gestational age, parity, body mass index, tobacco use, diabetes mellitus, chronic hypertension, hospital type and site, birthweight, history of cesarean delivery, malpresentation/breech, simplified Bishop score, insurance, marital status, and steroid use. Among the 460 women with induction (50%), 47% of deliveries were vaginal. By gestational age, 24 to 27 6/7, 28 to 31 6/7, and 32 to 33 6/7, the induction of labor success rates were 38% (12 of 32), 39% (70 of 180), and 54% (132 of 248), respectively. Induction of labor compared with planned cesarean delivery was less likely to be associated with placental abruption (adjusted relative risk, 0.33; 95% confidence interval, 0.16-0.67), wound infection or separation (adjusted relative risk, 0.23; 95% confidence interval, 0.06-0.85), and neonatal asphyxia (0.12; 95% confidence interval, 0.02-0.78). Women with vaginal delivery compared with those with failed induction of labor had decreased maternal morbidity (adjusted relative risk, 0.27; 95% confidence interval, 0.09-0.82) and no difference in neonatal outcomes. About half of women with preterm preeclampsia who attempted an induction had a successful vaginal delivery. The rate of successful vaginal delivery increases with gestational age. Successful induction has the benefit of preventing maternal and fetal comorbidities associated with previous cesarean deliveries in subsequent pregnancies. While overall rates of a composite of serious maternal and neonatal morbidity/mortality did not differ between induction of labor and planned cesarean delivery groups, women with failed induction of labor had increased maternal morbidity highlighting the complex route of delivery counseling required in this high-risk population of women.

Coviello EM ，Iqbal SN ，Grantz KL ，Huang CC ，Landy HJ ，Reddy UM ... -  《-》

Term cesarean breech delivery in the first pregnancy is associated with an increased risk for maternal and neonatal morbidity in the subsequent delivery: a national cohort study.

Macharey G ，Toijonen A ，Hinnenberg P ，Gissler M ，Heinonen S ，Ziller V ... -  《-》

Prolonged second stage of labor and risk of subsequent spontaneous preterm birth.

Preterm birth is the leading cause of neonatal morbidity and death in the United States. Although many risk factors for spontaneous preterm birth have been elucidated, some women with a previous term delivery experience spontaneous preterm birth in the absence of any identifiable risk factors. Cervical trauma during a prolonged second stage of labor has been postulated as a potential contributor to subsequent spontaneous preterm birth. This study was designed to examine the relationship between the length of the second stage of labor in the first pregnancy and the risk of spontaneous preterm birth in the subsequent pregnancy. This was a retrospective cohort study of all women with 2 consecutive singleton deliveries at a single institution between July 2012 and June 2018, with the first delivery occurring ≥37 weeks of gestation. Multiparous women and those women who did not reach the second stage of labor in the first pregnancy were excluded. Prolonged second stage of labor was defined as ≥4 hours, based on the 75th percentile for this cohort and on recommendations from the National Institute of Child Health and Human Development. Very prolonged second stage of labor was defined as ≥7 hours, based on the 95th percentile for this cohort. The primary outcome was spontaneous preterm birth <37 weeks of gestation in the subsequent pregnancy. The Kruskal-Wallis test compared median values for nonparametric continuous variables; Fisher's exact tests compared proportions for categoric variables, and logistic regression generated odds ratios. A total of 1032 women met criteria for study inclusion, with an overall subsequent spontaneous preterm birth rate of 3.1%. Prolonged second stage of labor of ≥4 hours was identified in 24.4% (252/1032 women) of the cohort, with 70.6% (178/252 women) of this group delivering vaginally. There was no statistically significant difference in rate of spontaneous preterm birth in those with and without prolonged second stage of labor (4.4% [11/252 women] with prolonged labor vs 2.7% [21/780 women] without prolonged labor; P=.21; odds ratio, 1.6; 95% confidence interval, 0.8-3.5). Very prolonged second stage of labor of ≥7 hours was identified in 4.3% (44/1032 women) of the cohort, with 45.4% (20/44 women) of this group delivering vaginally. There was a significantly higher rate of spontaneous preterm birth in those with very prolonged second stage of labor compared with those without prolonged labor (9.1% [4/44 women] with prolonged labor vs 2.8% [28/988 women] without prolonged labor; P=.04; odds ratio, 3.4; 95% confidence interval, 1.1-10.2), although this finding did not persist after we controlled for the mode of first delivery (adjusted odds ratio, 1.55; 95% confidence interval, 0.65-3.73). Spontaneous preterm birth after very prolonged second stage of labor was identified in only 4 patients, all of whom had a cesarean delivery with the first pregnancy. A second stage of labor of ≥4 hours in the first pregnancy was not associated with an increased risk of subsequent spontaneous preterm birth and was associated with a high rate (>70%) of vaginal birth. A second stage of labor of ≥7 hours did not appear to be associated with an increased risk of preterm birth, when we adjusted for mode of first delivery. There was a nonsignificant increase in the risk of preterm birth in those who delivered via cesarean section after a second stage of labor of ≥7 hours.

Sobhani NC ，Cassidy AG ，Zlatnik MG ，Rosenstein MG ... -  《-》