The impact of prenatal phthalate exposure on language development trajectories in siblings of children with Autism

Language development is a critical part of human development that unfolds across time. We aimed to examine how prenatal phthalate exposure affects early childhood language development, utilizing a robust longitudinal analysis methodology. Participants were drawn from the Early Autism Risk Longitudinal Investigation (EARLI) (n = 251) and the Markers of Autism Risk in Babies - Learning Early Signs (MARBLES) (n = 393) cohorts that recruited pregnant mothers who previously had a child with autism (ASD). Expressive and receptive language development was measured using the Mullen Scales of Early Learning (MSEL) at ages 6,12, 24, and 36 months. Fourteen phthalate metabolites were assessed in first morning urine in each trimester of pregnancy. We used latent class growth analysis (LCGA) to determine language trajectories and measure their associations with prenatal phthalqaates. We found three trajectories for both expressive and receptive languages. Most of the phthalates measured were not significantly associated with language development, though metabolites of di(2-ethylhexyl) phthalate decreased the risk of belonging to an abnormal receptive language trajectory. These observations, along with general trends observed within molecular weight classes, were largely consistent with prior literature.