The discussion on the safety of thimerosal-containing vaccines (TCVs) and their impact on child development it́s very relevant. Methods: This is a cohort study with mother-child dyads who received prenatal care in the Unified Health System. The domains of motor, cognitive and language development were evaluated in children between 24 and 36 months of age. Data on vaccination were obtained through the child's immunization record. A linear regression analysis was carried out considering possible confounders. Results: In bivariate analyses, motor and language development were associated with TCVs (p < 0.05). However, in the multivariate analysis, this association was not maintained (p > 0.05). These results indicate that the use of TCVs is not associated with child development. The importance of this study is summarized in transmitting relevant information regarding public health, based on reliable data.