Introduction: Obstetric anal sphincter tear (OAST) is associated with anal incontinence. Episiotomy was proposed as a form of protection of the anal sphincter at delivery; however, several studies have shown that routine use of episiotomy does not reduce the risk of OAST. Objective: This study aims to analyse whether the reduction in the rate of episiotomy in a school hospital in Brazil was associated with an increase in the incidence of obstetric lacerations of the anal sphincter, in addition to associated factors. Methods: Observational, cross-sectional and retrospective study. We included all vaginal deliveries of single pregnancies, cephalic presentation, from 34 weeks of gestational age, performed in 2011-2012 (liberal episiotomy) and 2015-2016 (restricted episiotomy), and compared in relation to the rate of mediolateral episiotomy and OAST. Results: 4268 births were analysed (2043 in 2011-2012 and 2225 in 2015-2016). The episiotomy rate decreased from 59.4% to 44.2% (p ≤ 0.0001). In 2011-2012, there were 10 obstetric anal sphincter lacerations in 2043 births (0.48%), while in the period 2015-2016 there were 31 lacerations in 2225 births (1.39%). There was interaction when comparing the two periods in relation to the episiotomy and the occurrence of OAST (p ≤ 0.0001). Factors associated with OAST were labor induction and shoulder dystocia. Conclusion: There was an increase in the rate of lacerations of the anal sphincter with use of restrictive episiotomy. However, this increase occurred both in deliveries with and in deliveries without episiotomy.

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