Background: The purpose of this study was to examine the risk of preterm birth (PTB) in relation to serious life events experienced during pregnancy in Peruvian women. Methods: This case-control study included 479 PTB cases and 480 term controls. In-person interviews asked information regarding sociodemographics, medical and reproductive histories, and serious life events experienced during pregnancy. Multivariate logistic regression procedures were used to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CIs). Results: Compared with women who did not experience a serious life event during pregnancy, those who experienced the following life events had a more than two-fold increased odds of PTB: death of first-degree relative (adjusted OR 2.10; 95% CI 1.38–3.20), divorce or separation (adjusted OR 2.09; 95% CI 1.10–4.00), financial troubles (adjusted OR 2.70; 95% CI 1.85–3.94), or serious fight with partner (adjusted OR 2.40; 95% CI 1.78–3.17). Women who experienced any serious life events during pregnancy had higher odds (adjusted OR 2.29; 95% CI 1.65–3.18) of suffering spontaneous preterm labor and preterm premature rupture of membranes (adjusted OR 2.19; 95% CI 1.56–3.08), compared with women who did not experience any such events. Associations of similar directions and extent were observed for severity of PTB (ie, very, moderate, or late PTB). The magnitude of the associations increased as increased frequency of serious life events (Ptrend <0.001). Conclusion: Experiencing serious life events during pregnancy was associated with increased odds of PTB among Peruvian women. Interventions aimed at assisting women experiencing serious life events may reduce the risk of PTB. Future studies should include objective measures of stress and stress response to understand better the biological underpinnings of these associations
