Association Between Neuraxial Labor Analgesia and Perineal Outcomes in Vaginal Deliveries: A Retrospective Cohort Study

PROTOCOL SYNOPSIS Setting: Delivery suite of Guangxi Zhuang Autonomous Region Maternal and Child Health Hospital (tertiary obstetric center), Nanning, China.Study period: 1 January 2022 to 31 December 2024.Population:Women undergoing vaginal birth (spontaneous or forceps-assisted) during the study period.Exposure:Receipt of neuraxial labor analgesia (epidural analgesia) vs no neuraxial labor analgesia.Sample size：10,009 vaginal births screened; 9,979 included in the final analytic cohort (analgesia n=7,658; non-analgesia n=2,321).Primary endpoint:Mutually exclusive perineal outcome categories: intact perineum; mild laceration (1st degree); moderate-to-severe laceration (>=2nd degree; 2nd-3rd combined); episiotomy.Key covariates:(prespecified) Maternal age (advanced maternal age >=35), BMI category, gestational age at birth (preterm