Length of the second stage of labor as a predictor of perineal outcome after vaginal delivery

OBJECTIVE: To evaluate possible risk factors for spontaneous and induced perineal damage during vaginal delivery. STUDY DESIGN: A prospective, observational study was conducted with 300 patients at 37-42 weeks of singleton gestation who presented in active labor. Sociodemographic data, birth circumstances and past medical history were obtained upon admission. Perineal damage was assessed before repair and 24 hours postpartum. A multiple logistic regression model was constructed to investigate independent risk factors for spontaneous perineal lacerations. RESULTS: Of 300 women included, 139 were primiparas. Episiotomy was performed in 32% of the population (62% in primiparas, 6% in multiparas). Spontaneous perineal tears requiring suturing occurred in 28%. Severe perineal tears (grades 3 and 4) occurred in 1%. Risk factors for adverse perineal outcome in the non-episiotomy group included younger maternal age, non-Israeli ethnic background, use of epidural analgesia, nulliparity, shorter interval since last vaginal delivery, longer active phase and prolonged second stage. Prolonged second stage (> 40 minutes) and low parity were independent risk factors for verineal tears in a multivariable analysis. CONCLUSION: Identifying women in specific subgroups at high risk for perineal lacerations may minimize perineal damage. Women with a prolonged second stage of labor and low parity are prone for spontaneous damage and therefore deserve special attention.