Introduction: To determine the impact of prior vaginal birth on neonatal and maternal outcomes among individuals undergoing a trial of labor after two cesarean births.
Materials and methods: This was a cross-sectional study using the U.S. National Vital Statistics 2014-2018 period linked birth and infant death data. Inclusion criteria were term, cephalic, singleton pregnancies with two prior cesarean births. The primary exposure variable was a trial of labor after cesarean vs prelabor repeat cesarean birth. Cohorts were defined by the presence or absence of a prior vaginal birth. The primary outcome was a composite of adverse neonatal outcomes (Apgar score <5 at 5 min, assisted ventilation >6 h, neonatal seizures, or neonatal death within 27 days). Secondary outcomes included a maternal composite and the cesarean birth rate. Propensity score matching was used to account for baseline differences in treatment allocation within each cohort, and conditional logistic regression assessed the association between the exposure and outcomes.
Results: The composite neonatal adverse outcome was significantly higher in those undergoing a trial of labor after cesarean compared to prelabor repeat cesarean birth in both individuals without a prior vaginal birth (8.2 vs 11.6 per 1000 live births, OR 1.41; 95% CI 1.12-1.70) and with a prior vaginal birth (9.6 vs 12.4 per 1000 live births, OR 1.30; 95% CI 1.08-1.57). The composite maternal adverse outcome was significantly higher among individuals without a prior vaginal birth undergoing trial of labor after cesarean (6.0 vs 9.5 per 1000 live births, OR 1.59; 95% CI 1.26-2.09), but was similar in those with a prior vaginal birth (7.9 vs 9.3 per 1000 live births, OR 1.18; 95% CI 0.97-1.46).
Conclusion: In individuals with two prior cesarean births, trial of labor after cesarean was associated with increased neonatal adverse outcomes when compared to prelabor repeat cesarean birth, irrespective of a history of vaginal birth. In individuals with a prior vaginal birth, the composite maternal adverse outcome was not elevated in the trial of labor cohort.
Keywords: Trial of labor after cesarean; cesarean birth; maternal morbidity; neonatal morbidity; uterine rupture; vaginal birth after cesarean.