Introduction: Perineal trauma is an important complication for women after giving birth. Objective: To evaluate the prevalence of perineal trauma and its associated factors in nulliparous. Methods: A retrospective cohort study was carried out, through the analysis of the medical records of women with singleton pregnancy who achieved vaginal birth of a live infant, in 2017, in a maternity hospital. Data collection involved information about demographic, obstetric, and clinical data from nulliparous women, and infant birthweight. Univariate and multivariate logistic analyses were performed to verify the association of perineal trauma with the variables assessed, with significant variables remaining in the model (p<0.05), through a stepwise strategy. Results: A total of 326 medical records were analyzed. The percentage of perineal trauma was 60%. In the multivariate analysis, the use of oxytocin increased the chance of perineal trauma by 730%. In addition, the adoption of squatting position and hands and knees decreased the chances of perineal trauma by 81% and 97%, respectively, in comparison with those who adopted the lithotomy position, during the second stage labor. Conclusion: The rate of perineal laceration was high, but the severity was low. The use of oxytocin is associated with the presence of trauma and the squatting position and hands and knees, especially, have contributed to the protection of the perineum.