Prenatal phthalate exposure and neurodevelopmental delay in early childhood (1 to 3 years): An Environmental influences on Child Health Outcomes (ECHO) study

Phthalates are widely used in consumer products and are recognized as endocrine disruptors. Prenatal exposure to phthalates has been associated with various adverse health outcomes, including preterm birth and impaired fetal growth, and growing attention is being paid to their potential impact on child neurodevelopment. However, previous epidemiological studies examining prenatal phthalate exposure and child neurodevelopment have produced inconsistent or inconclusive findings, and evidence on phthalate mixtures remains limited. In this study, we utilized data from the Environmental influences on Child Health Outcomes (ECHO) Cohort to investigate associations between urinary biomarkers of prenatal phthalate exposure, both individually and as a mixture, and likelihood of neurodevelopmental delay (NDD) in offspring at ages 1 to 3 years. This study included 2378 pregnant person-child dyads from 10 ECHO cohorts who had measurements of NDD odds assessed using the Ages and Stages Questionnaire, Third Edition (ASQ-3). Our single-pollutant analyses revealed mixed findings. Higher prenatal exposure to certain phthalates was associated with higher odds of NDD across multiple domains, including motor and problem-solving skills, with evidence of effect modification by child sex. Conversely, we observed negative associations between specific prenatal phthalate concentrations and lower odds of NDD, particularly in communication domain. From mixture analyses, however, no significant associations were observed between the overall phthalate mixture and NDD odds in most domains, except for negative association for the personal-social domain. Further investigation into the biological mechanisms underlying these relationships, as well as more detailed evaluations of phthalate mixtures, will help advance our understanding of how prenatal phthalate exposure may influence early childhood neurodevelopment.