Conflicting results have been reported on the possible role of life events in triggering OCD onset. Moreover, pregnancy and/or delivery, among life events, appear to influence the OCD course and, in some cases, appear related to its onset. Our purpose was to assess the occurrence of potentially traumatizing events among patients with OCD. The study also provides an initial exploration of the association between OCD and pregnancy or delivery. The number and type of stressful life events which occurred in the 12 months before the onset of OCD were determined for both OCD patients (N = 68, 33 women and 35 men) and a group of comparison subjects (N = 68, 33 women and 35 men) by using a semistructured interview in accordance with Paykel's list. The results did not show a significant excess of life events in patients compared with healthy subjects. No differences were detected between OCD patients according to gender. When examining the type of events, OCD female individuals were found to be more likely than normal female subjects to report exposure to postpartum events, and high rates of obstetric complications were observed in these patients. Subjects with postpartum OCD had significantly higher rates of aggressive obsessions to harm the newborn. OCD male subjects did not show an association between a specific event and onset of the disorder. The findings confirm that the postpartum period represents a risk factor for OCD in some individuals, and suggest that obstetric complications may be relevant to the development of the disorder.