To investigate the occurrence of developmental defects of enamel (DDE) in the primary teeth of children aged 24-36months and their association with early-life events. This study was undertaken with children aged 24-36months in Pelotas, Southern Brazil. Information on demographic and socioeconomic characteristics, events occurring during pregnancy and neonatal events was collected previously. In this study, information on the health-related behaviours of mothers and children was collected using questionnaires and information about children's oral health was achieved through clinical oral examination. The outcome, the prevalence of DDE (≥1), was determined using the DDE index (FDI). Bivariate and multivariate logistic regression analyses were performed. Five hundred and three mother/child dyads were evaluated, and 13.1% of the children had DDE. Multivariate analysis showed that children with Apgar scores less than 7 had around 2.5-fold higher odds of developing DDE than children with Apgar scores between 7 and 10 (OR=2.78; 95% confidence interval [CI], 1.35-5.73). The analysis of different types of enamel defects shows that the presence of hypoplasia (OR 3.13; 95% CI, 1.35-7.27) and diffuse opacities (OR 3.95; 95% CI, 1.68-9.27) remained associated in adjusted analysis with Apgar scores. Early-life events may cause DDE. A lower Apgar score was associated with a higher prevalence of enamel defects.