Risk factors associated with third- and fourth-degree perineal lacerations in singleton vaginal deliveries: a...

Perineal lacerations are a common complication of vaginal birth, affecting approximately 85 % of patients. Third-and fourth-degree perineal lacerations (3/4PL) remain a significant cause of physical and emotional distress. We aimed to perform an extensive assessment of potential risk factors for 3/4PL based on a comprehensive and current US population database.

Retrospective population-based cohort analysis based on the US Centers for Disease Control and Prevention Natality Live Birth online database between 2016-2020. Baseline characteristics were compared between women with 3/4PL and without 3/4PL by using Pearson's Chi-squared test with statistical significance set at p<0.05. Bonferroni correction was used to account for multiple comparisons. Multivariable logistic regression was performed to evaluate the association between a variety of potential risk factors and the risk of 3/4P.

Asians/Pacific Islanders had the highest risk of 3/4PL (2.6 %, aOR 1.74). Gestational hypertension and preeclampsia were associated with increased risk of 3/4PL (aOR 1.28 and 1.34, respectively), as were both pre-gestational and gestational diabetes (aOR 1.28 and 1.46, respectively). Chorioamnionitis was associated almost double the risk (aOR 1.86). Birth weight was a major risk factor (aOR 7.42 for greater than 4,000 g), as was nulliparity (aOR 9.89).

We identified several maternal, fetal, and pregnancy conditions that are associated with an increased risk for 3/4PL. As expected, nulliparity and increased birth weight were associated with the highest risk. Moreover, pregestational and gestational diabetes, hypertensive disorders of pregnancy, Asian/Pacific Islander race, and chorioamnionitis were identified as novel risk factors.