Factors associated with spontaneous perineal lacerations in deliveries without episiotomy in a university maternity hospital in the city of Recife, Brazil: a cohort study

Objectives: The objective of this study is to determine factors associated with spontaneous perineal laceration in low-risk pregnant women who delivered vaginally without episiotomy in a university maternity hospital in Recife, Pernambuco, Brazil.Methods: A prospective cohort study was conducted with 222 low-risk, full-term pregnant women admitted in labor with a single fetus in cephalic presentation. Women with malformed fetuses were excluded from the study. The variables analyzed were: the frequency and severity of lacerations, the women's biological, sociodemographic, clinical and obstetrical characteristics, neonatal characteristics, and data on their deliveries and procedures. For the data analysis, risk ratios and their 95% confidence intervals were calculated. A significance level of 5% was adopted and multiple regression analysis was performed.Results: Spontaneous first-degree perineal tears were registered in 47% of the women, second-degree tears in 31%, and third degree tears in only 1.8%. There were no cases of fourth-degree tears. Having experienced normal childbirth previously constituted a protective factor against vaginal tearing (OR= 0.46; 95%CI: 0.23-0.91; p=.027).Conclusion: The principal protective factor against spontaneous lacerations was having experienced normal childbirth previously. Intrapartum strategies aimed at protecting the perineum and pelvic floor muscle training during prenatal care should be encouraged in these women.