Maternal Mediterranean-Style Diet During Pregnancy and Child Social Impairment as Measured by the Social Responsiveness Scale.

While previous studies have examined the role of individual micronutrients in autism spectrum disorder (ASD), limited evidence exists on how maternal dietary patterns during pregnancy relate to broader social and communication outcomes. This study aimed to assess the association between adherence to a Mediterranean-style diet during pregnancy and measures of social impairment in a racially diverse, prospective birth cohort. We analyzed 821 mother-child pairs from the Boston Birth Cohort, including 52 children with an ASD diagnosis. Maternal Mediterranean-style Diet Scores (MSDS) during pregnancy were calculated using food frequency questionnaires administered 24-72 h after delivery. Child social impairment was assessed using Social Responsiveness Scale (SRS). Restricted cubic spline models were used to explore potential non-linear relationships between MSDS and SRS total scores. Linear regression models were used to quantify associations between MSDS tertiles and children's SRS total scores and scores across five SRS subdomains. An L-shape association was observed between maternal MSDS and SRS total scores. Compared to the children of mothers in the lowest MSDS tertiles, those in the middle (beta (95% CI) = -4.95 (-9.59, -0.31)) and highest tertiles (-5.13 (-9.48, -0.79)) had significantly lower SRS total scores, indicating reduced social impairment. Associations were particularly pronounced in the social cognition and social communication subdomains. Greater maternal adherence to a Mediterranean-style diet during pregnancy was associated with better social interaction and communication development in children. These findings underscore the critical role of maternal nutrition in child neurodevelopment, highlighting potential targets for early risk assessment and prevention efforts.