Is there an optimal inter-delivery interval in women who underwent trial of labor after cesarean delivery (TOLAC)?

An inter-delivery interval (IDI) that is too short or too long increases the risk of adverse maternal and neonatal outcomes. However, the optimal IDI for trial of labor after cesarean delivery (TOLAC) remains unclear. We performed a multicenter, electronic medical record-based, retrospective cohort study that included 1080 pregnant women who had one or two cesarean deliveries and underwent TOLAC. Data on maternal and neonatal outcomes were collected from the electronic record system. In multivariable analysis, the incidences of postpartum hemorrhage, preterm birth, and low birth weight were significantly increased in women with an IDI of < 24 months than in those with a normal interval (24–59 months). Infections, transfusion, and neonatal unit admission were significantly increased in women with an IDI of ≥ 120 months than in those with a normal interval. In conclusion, we found that an IDI < 24 months or ≥ 120 months increased the risk of major maternal and neonatal outcomes. We recommend that the optimal interval for women who underwent TOLAC should be 24 to 119 months.