BACKGROUND:Existing literature on the impact of the course of maternal distress symptoms in the perinatal period and beyond has mainly focused on one source of distress (e.g., anxiety or depression) and only selected aspects of child development. This study examined the relative impact of trajectories of maternal depression, anxiety, and stress symptoms from mid-pregnancy to early childhood on child communication, gross motor, fine motor, problem solving, and personal social development at three years of age. METHODS:Data were analyzed from 1983 mother-child dyads who participated in the three-year follow-up of the All Our Families (AOF) study. Maternal distress and child development across five domains were measured using validated tools. Latent class analysis (LCA) was conducted to identify trajectories of maternal distress over time. Multivariable logistic regression was used to explore the relationship between the trajectories and child development while adjusting for the covariates. RESULTS:At age three years, 5.2% of children were at risk communication delay; 12.7% for gross motor delay; 15.4% for fine motor delay; 11.2 for problem solving delay; and 5.6% for personal-social delay on ASQ-3 domains. Multivariable analysis showed children born to mothers with persistent high anxiety symptoms from pregnancy to 3-years postpartum had an increased risk of delays in communication and personal-social domains. LIMITATIONS:The use of self-reported maternal mental health symptoms and maternal reported child development are the study limitations. CONCLUSIONS:The impact of high levels of maternal anxiety symptoms on the increased risk of child developmental delay in communication and personal-social domains highlights the importance of early intervention and addressing maternal anxiety from pregnancy through early childhood.