Maternal Iodine Status During Pregnancy and Child Neurodevelopment: A Systematic Review and Dose–Response Meta-Analysis of Prospective Cohort Studies

BACKGROUND: Iodine deficiency during pregnancy remains a leading cause of preventable neurodevelopmental impairment worldwide, yet quantitative characterization of the dose-response relationship between maternal iodine status and child neurodevelopment is lacking. METHODS: A systematic search of PubMed, Embase, the Cochrane Library, and Web of Science was conducted for prospective cohort studies published up to February 2026 reporting associations between maternal iodine status and child neurodevelopmental outcomes across at least three exposure categories. All continuous effect estimates were converted to standardized mean differences (Hedges' g) to permit pooling across heterogeneous assessment instruments, and meta-analyses were stratified by neurodevelopmental domain (cognitive, language, motor, behavior, academic). A two-stage dose-response meta-analysis was used to characterize non-linearity. Risk of bias was evaluated using the Newcastle-Ottawa Scale (NOS). RESULTS: = 0.436 for UI/Cr), and these findings should therefore be interpreted as exploratory. CONCLUSIONS: Suboptimal maternal iodine status during pregnancy was associated with modest decrements in child neurodevelopmental performance, with exploratory dose-response analyses suggesting that the fitted curves approached their maximum within a mid-range of dietary iodine intake. Although statistical evidence for quadratic non-linearity was attenuated after consolidating overlapping cohorts, the directional pattern across indicators remained consistent with an inverted U-shaped relationship, supporting maintenance of adequate but not excessive iodine nutrition during pregnancy.