Trial of labor following one previous cesarean delivery: the effect of gestational age.

PURPOSE: To stratify maternal and neonatal outcomes of trials of labor after previous cesarean delivery (TOLAC) by gestational age.

METHODS: Retrospective cohort study of all singleton pregnancies with one previous cesarean delivery in TOLAC at term between 2007 and 2014. We compared outcomes of delivery at an index gestational week, with outcomes of women who remained undelivered at this index gestational week (ongoing pregnancy). Odds ratios and 95% confidence intervals were adjusted for maternal age, previous vaginal delivery, induction of labor, epidural use, presence of meconium, and birth weight > 4000 g.

RESULTS: Overall, 2849 women were eligible for analysis. Of those, 2584 (90.7%) had a successful TOLAC and 16 women (0.56%) had uterine rupture. Those rates did not differ significantly for any gestational age (GA) group. Following adjustment for possible confounders, GA was not found to be independently associated with adverse maternal or neonatal outcomes.

CONCLUSION: Among women at term with a single previous cesarean delivery, GA at delivery was not found to be an independent risk factor for TOLAC success or uterine rupture. We suggest that GA by itself will not serve as an argument for or against TOLAC.