Abstract
Objective: To determine rates of maternal and perinatal outcomes after induction of labor (IOL) at 39 weeks compared with expectant management.Methods: Cohort study of low risk women delivered between 39-42 weeks from 2015 to 2018. We excluded births with fetal abnormalities, previous cesarean, multiple pregnancies or those with spontaneous onset of labor (SOL) or indicated delivery at 39 weeks. Data was abstracted from National Center for Health Statistics birth files. Relative risks (aRR) were estimated with multivariable log-binomial regression. Main Outcome Measures: Maternal outcomes: chorioamnionitis (Triple I), blood transfusion, neonatal intensive care unit (NICU) admission, uterine rupture, cesarean delivery and cesarean hysterectomy. Fetal and infant outcomes: fetal death, 5-minute Apgar ≤3, prolonged ventilation, seizures, ICU admission, and death within 28 days. Results: There were 15,900,956 births, with 8,540,063 after exclusions. The IOL group included 1,177,790 births excluding women with diabetes or hypertensive disease. There were 3,835,185 births after 39 weeks excluding women with diabetes or chronic hypertension. With IOL at 39 weeks the risk for blood transfusion (p-value < 0.01; aRR 0.78; 95% CI [0.75-0.82]), Triple I (p-value < 0.01; aRR 0.71; 95% CI [0.70-0.73]) and cesarean delivery (p-value <0.01; aRR 0.87; 95% CI [0.87-0.88]) were lower, albeit increased risk of cesarean hysterectomy (p-value <0.01; aRR 1.23; 95% CI [1.07-1.41]). Neonates had a lower risk for 5-minute Apgar ≤3 (p-value < 0.01; aRR 0.68; 95% CI [0.66-0.71]), prolonged ventilation (p-value < 0.01; aRR 0.84; 95% CI [0.81-0.87]), NICU admission (p-value < 0.01; aRR 0.86; 95% CI [0.85-0.87]), and neonatal seizures (p-value <0.01; aRR 0.85; 95% CI [0.76-0.96]). There was no difference in risk for neonatal death 0.99% (p-value 0.99; aRR 1.00; 95%CI [0.99-1.00]), or fetal death (p-value 0.78; aRR 1.0002; 95%CI [0.99-1.002]. This benefit was greater compared with each subsequent week.Conclusions: Induction of labor at 39 weeks of gestation in a low risk cohort is associated a lower risk of cesarean delivery, transfusions and infection, as well as lower neonatal morbidity, without difference in fetal or neonatal death. This appears to be associated with increased risk for cesarean hysterectomy.
Impact of labor induction at 39 weeks gestation compared with expectant management on maternal and perinatal morbidity among a cohort of low-risk women
