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Background: Obstetric lesions of the anal sphincter (OASIS) are tears intersecting the structure of the anus after vaginal delivery. Our aim is to provide data on the incidence of OASIS and investigate potentially connected risk factors., Methods: This is a retrospective analysis of 464 parturient patients admitted to the AOU Maggiore della Carità, Novara (Italy), in the last ten years (2013-2023), comparing 116 cases (with OASIS) versus 348 controls (with no OASIS)., Results: The incidence of OASIS was 1.1%. Among the significant risk factors associated with the risk of severe perineal laceration in our sample, we observed nulliparity, previous caesarean sections, assisted reproduction technology, kilos gained during pregnancy, induced delivery, the use of oxytocin for augmentation, epidural analgesia, delivery after 40 weeks of gestation, position at delivery, the duration of labor, the application of a vacuum cup, newborn weight and head circumference., Conclusions: It was a challenge to find data on OASIS and on more preventable and modifiable risk factors. Beyond the improvement of the corresponding diagnostic and therapeutic tools, a new aim could be to stratify women giving birth based on possible risk factors.