Predictors of Third and Fourth-degree Perineal Lacerations

Objective: To identify factors related to pregnancy and childbirth that predispose to perineal trauma Methods: This is a retrospective cohort study consisting of 2 groups of patients. The first group was comprised of patients who sustained 3rd or 4th-degree lacerations. They were compared with all other patients who delivered vaginally without 3rd or 4th-degree lacerations. Variables of interest were compared by univariate analysis utilizing a t test and Fisher exact test. Then a multivariate analysis by logistic regression was conducted to determine which of these variables identified in the univariate analysis were independently associated with the occurrence of 3rd and 4th-degree lacerations. All nonsignificant variables were removed from the initial model to yield the final model Results: The risk of 3rd and 4th-degree lacerations increases with 1) the use of forceps or vacuum (OR = 3.04, CI = 2.42, 3.84), 2) the use of episiotomy (OR = 6.94, CI = 5.36, 8,99), 3) the presence of hypertension (OR = 1.63, CI = .998, 1.714), 4) increasing birth weight (OR = 1.001, CI = 1.001, 1.001). The risk of 3rd and 4th-degree lacerations decreases with 1) 1 or more previous deliveries (OR = .239, CI = .183, .314) and 2) increasing prepregnancy maternal weight (OR = .990, CI = .986, .994) Conclusions: Our study confirms what prior studies have shown: operative delivery and episiotomy use are associated with perineal lacerations. Additionally, we have identified other risk factors that can be considered before delivery, which an obstetrician might use in weighing the risks and benefits of different modes of delivery.