Risk of obstetric anal sphincter injury among women who birth vaginally after a prior caesarean section: A state-wide cohort study

Abstract

Objective: Vaginal birth after caesarean (VBAC) has been suggested to be associated with an increased risk of obstetric anal sphincter injury (compared with primiparous women who birth vaginally). However, prior studies have been small or have used outdated methodology. We set out to validate whether the risk of obstetric anal sphincter injury among women having their first VBAC is greater than that among primiparous women having a vaginal birth. Design: State-wide retrospective cohort study. Setting: Victoria, Australia. Population: All births (455 000) between 2009 and 2014. Methods: The risk of severe perineal injury between the first vaginal birth and the first VBAC was compared, after a..