Intrapartum Febrile Morbidity and Maternal Birth Trauma After Vaginal Delivery: A Parity-Stratified Retrospective Cohort Study

Objective: We aimed to evaluate the association between intrapartum febrile morbidity and maternal birth trauma among women undergoing vaginal delivery, with stratification by parity. Methods: This retrospective cohort study included women with singleton, cephalic, vaginal deliveries at a university-affiliated medical center between 2018 and 2024, excluding multiple gestations and cesarean deliveries. The primary exposure was intrapartum febrile morbidity, defined as maternal intrapartum temperature ≥38.0 °C, with or without clinical chorioamnionitis. The primary outcome was maternal birth trauma, including first- through fourth-degree perineal lacerations, cervical lacerations, or episiotomy. Multivariable logistic regression models were used to assess the independent association between intrapartum febrile morbidity and birth trauma. Analyses were additionally stratified by parity. Results: Among 21,736 women with vaginal deliveries included in the study, birth trauma occurred in 41.8% of deliveries (9075/21,736). Intrapartum febrile morbidity was more common among women with birth trauma compared with those delivering with an intact perineum (4.2% vs. 1.8%, p < 0.001). After adjustment for confounders, intrapartum febrile morbidity remained independently associated with birth trauma in the overall cohort (adjusted odds ratio [aOR], 1.5; 95% CI, 1.1–1.8). In parity-stratified analyses, the association persisted among multiparous women (aOR 1.8; 95% CI, 1.2–2.9) but was not statistically significant among nulliparous women (aOR, 1.3; 95% CI, 0.9–1.7). Nulliparity and operative vaginal delivery were the strongest predictors of birth trauma. Conclusions: These findings suggest that intrapartum febrile morbidity may identify women at increased risk of lower genital tract trauma beyond established mechanical risk factors.