Risk Factor Analysis for Spontaneous Perineal Injury in Nulliparous Women

Abstract

Purpose: We sought to identify risk factors for spontaneous perineal tears of all degrees during vaginal delivery in nulliparous women. Material and Methods: We studied 725 consecutive term, singleton, spontaneous vaginal deliveries in nulliparous women at the University Hospital of Vienna. Risk factors for perineal tears were evaluated using univariate and multivariate logistic regression analysis. Medical and obstetric records were reviewed for the following characteristics: maternal age, duration of the second stage of labor, donation of oxytocin, use of episiotomy, use of epidural analgesia, premature rupture of the membranes (PROM), delivery position, fetal birth weight and occurrence and severity of perineal tears. Results: 74% of nulliparous parturients had no detectable tears. An overall rate of perineal trauma of 26% was found, resulting in 16% first degree tears and 9% second degree tears, whereas third degree perineal tears only occurred in a small percentage (0.6%). A univariate analysis revealed that absence of episiotomy (p = 0.0001) and supine position (p = 0.033) increased the risk of perineal tears during first spontaneous vaginal delivery. Age, the use of epidural analgesia, the donation of oxytocin, PROM and the duration of the second stage of labor showed no statistically significant influence on the occurrence of perineal lacerations (p>0.05). Furthermore, a multiple logistic regression model revealed that absence of episiotomy (p=0.0001) remained independently associated with perineal lacerations. Additionally high women's age (p = 0.027) and large fetal size (p = 0.049) were independently associated with an increased risk of perineal lacerations. Conclusions: Our results identified the absence of episiotomy, high women's age and large fetal size as independent risk factors for perineal tears of all degrees in nulliparous women. We therefore suggest that selective use of episiotomy could minimize perineal trauma during first spontaneous vaginal delivery.