This study aimed to verify the course of maternal anxiety disorders and its impact on child development of toddlers. This is a cohort study that followed 497 pregnant adolescents who received antenatal care in the public health service in a southern city in Brazil. We assessed maternal anxiety disorders during gestation, postpartum, and when children were 2-3 years old and we evaluated child development in toddlerhood. We performed a structured modelling approach to compare the effect of three different hypothesized life course models (accumulation, critical period, and mobility) of maternal anxiety on child development. The course of maternal anxiety manifests in different ways in each dimension of child development. However, only child cognitive development was directly impacted by maternal anxiety disorders (B -4.05; 95%CI -7.16; -0.93). Research on the impact of life course models of anxiety disorders is needed to help the implementation of interventions to prevent future negative outcomes.