Maternal Dietary Pattern in Pregnancy and Behavioral Outcomes at 4 Years of Age in the Piccolipiù Cohort: Potential Sex-Related Differences

: Background: The fetal period is critical for neurodevelopment, with maternal diet emerging as a key environmental factor influencing long-term child health. This study investigated the associations between maternal dietary patterns during pregnancy and neurocognitive and behavioral outcomes in 4-year-old children, with a particular focus on sex-related differences. Methods: We used data from the Piccolipiù Italian birth cohort, including 2006 mother/child pairs. Maternal dietary intake during pregnancy was assessed via a questionnaire and categorized into distinct patterns using Principal Component Analysis (PCA). Child neurodevelopment was evaluated at age 4 using the Wechsler Preschool and Primary Scale of Intelligence (WPPSI) and the Child Behavior Checklist (CBCL 1.5-5). Linear and logistic regression models were employed, adjusting for potential confounders and stratifying by child sex. Results: Two major maternal dietary patterns were identified: "Processed and high-fat foods" and "Fresh foods and fish". Higher maternal adherence to the "Processed and high-fat foods" pattern was associated with increased externalizing behaviors in offspring (β = 0.88; 95%CI 0.28-1.49; p = 0.004). In males, this pattern was associated with an increased clinical risk of Attention Deficit Hyperactivity Disorder (ADHD) (OR (Odds Ratio) = 1.13; 95%CI: 1.02-1.26; p = 0.021). Conclusions: Our findings indicate that maternal consumption of a diet rich in processed and high-fat foods during pregnancy is associated with increased behavioral problems in children, with sex-specific vulnerabilities: slightly higher externalizing behaviors in girls and an increased risk of ADHD in boys. These results underscore the importance of promoting healthy maternal dietary patterns during pregnancy as a targeted early prevention strategy for supporting child neurodevelopment.