Episiotomy to prevent obstetric anal sphincter injuries during instrumental delivery in nulliparous women: a national prospective comparative cohort study.

Background: We are lacking data with a high level of evidence on the use of episiotomy during instrumental delivery to prevent anal sphincter injury, which nonetheless presents the highest risk.

Objective: Our main objective was to assess the protective effect of episiotomy against obstetric anal sphincter injury in nulliparous women during instrumental delivery according to type of instrument. We also investigated its impact on immediate maternal and neonatal morbidity.