Induction of labor vs expectant management among low-risk patients with 1 prior cesarean delivery.

BACKGROUND

Studies that have compared induction of labor in individuals with 1 prior cesarean delivery to expectant management have shown conflicting results.

OBJECTIVE

To determine the association between clinical outcomes and induction of labor at 39 weeks in a national sample of otherwise low-risk patients with 1 prior cesarean delivery.

STUDY DESIGN

This cross-sectional study analyzed 2016 to 2021 US Vital Statistics birth certificate data. Individuals with vertex, singleton pregnancies, and 1 prior cesarean delivery were included. Patients with prior vaginal deliveries, delivery before 39 weeks 0 days or after 42 weeks 6 days of gestation, and medical comorbidities were excluded. The primary exposure of interest was induction of labor at 39 weeks 0 days to 39 weeks 6 days compared to expectant management with delivery from 40 weeks 0 days to 42 weeks 6 days. The primary outcome was vaginal delivery. The main secondary outcomes were separate maternal and neonatal morbidity composites. The maternal morbidity composite included uterine rupture, operative vaginal delivery, peripartum hysterectomy, intensive care unit admission, and transfusion. The neonatal morbidity composite included neonatal intensive care unit admission, Apgar score less than 5 at 5 minutes, immediate ventilation, prolonged ventilation, and seizure or serious neurological dysfunction. Unadjusted and adjusted log binomial regression models accounting for demographic variables and the exposure of interest (induction vs expectant management) were performed. Results are presented as unadjusted and adjusted risk ratios with 95% confidence intervals.

RESULTS

From 2016 to 2021, a total of 198,797 individuals with vertex, singleton pregnancies, and 1 prior cesarean were included in the primary analysis. Of these individuals, 25,915 (13.0%) underwent induction of labor from 39 weeks 0 days to 39 weeks 6 days and 172,882 (87.0%) were expectantly managed with deliveries between 40 weeks 0 days and 42 weeks 6 days. In adjusted analyses, patients induced at 39 weeks were more likely to have a vaginal delivery when compared to those expectantly managed (38.0% vs 31.8%; adjusted risk ratio 1.32, 95% confidence interval 1.28, 1.36). Among those who had vaginal deliveries, induction of labor was associated with increased likelihood of operative vaginal delivery (11.1% vs 10.0; adjusted risk ratio 1.15, 95% confidence interval 1.07, 1.24). The maternal morbidity composite occurred in 0.9% of individuals in both the induction and expectant management groups (adjusted risk ratio 0.92, 95% confidence interval 0.79, 1.06). The rates of uterine rupture (0.3%), peripartum hysterectomy (0.04% vs 0.05%), and intensive care unit admission (0.1% vs 0.2%) were all relatively low and did not differ significantly between groups. There was also no significant difference in the neonatal morbidity composite between the induction and expectant management groups (7.3% vs 6.7%; adjusted risk ratio 1.04, 95% confidence interval 0.98, 1.09).

CONCLUSION

When compared to expectant management, elective induction of labor at 39 weeks in low-risk patients with 1 prior cesarean delivery was associated with a significantly higher likelihood of vaginal delivery with no difference in composite maternal and neonatal morbidity outcomes. Prospective studies are needed to better elucidate the risks and benefits of induction of labor in this patient population.