Comparing a trial of labour with planned caesarean after one previous caesarean delivery: a protocol for a population-based cohort study

The caesarean section rate has risen. An increasing number of women who have had one previous caesarean section need to consider mode of delivery in a subsequent pregnancy. Both trial of labour after caesarean (TOLAC) and planned repeat caesarean section are associated with maternal and perinatal risks. We will undertake a retrospective cohort study of recorded livebirths for women who have had one previous caesarean section in the United States from 2011 to 2024. Using multivariable logistic regression, we will examine the relationship between the intended mode of delivery at 39 weeks gestational age (TOLAC at 39 weeks or any mode of delivery at 39 to 43 weeks versus caesarean section without trial of labour at 39 weeks) and important maternal and neonatal outcomes. We will also examine the relationship between TOLAC and caesarean section without a trial of labour for maternal outcomes at 20 to 43 weeks and for perinatal outcomes at 37 to 43 weeks. Due to the large data size, this study will be able to report on rare maternal and perinatal outcomes and contribute to evidence that influences important decisions about mode of delivery after one caesarean section.