Prenatal complications and sex modify the BMI-blood pressure relationship in children.

BACKGROUND: Prenatal factors may influence cardiovascular risk in offspring; however, their role in modifying the association between body mass index (BMI) and blood pressure (BP) in children remains unclear. METHODS: This cross-sectional study included 769 children (6-13 years) without chronic conditions affecting BP. Systolic and diastolic BP were measured using a standardized protocol. Prenatal and familial data were obtained from parent-completed questionnaires. Associations were examined using hierarchical linear regression models with adjustment for age, sex, height, BMI, birth weight (z-score), and socioeconomic factors. Interaction terms were incorporated to assess effect modification. RESULTS: BMI was the strongest predictor of both systolic and diastolic BP. Among prenatal factors, only pregnancy complications were associated with higher systolic BP (approximately +2.5 mmHg). No significant associations were observed for other prenatal variables. Interactions between BMI and pregnancy complications were identified for both BP measures. The BMI-BP association was stronger in children from uncomplicated pregnancies than in those exposed to prenatal complications. A BMI-sex interaction was also observed for systolic BP, with a stronger association in girls. CONCLUSIONS: BMI is a determinant of BP in children, but its effect may be modified by prenatal conditions. These findings support a role of developmental factors in shaping cardiovascular risk. IMPACT: Body mass index (BMI) is one of the major modifiable determinants of blood pressure in children; however, its influence varies across individuals. Pregnancy complications modify the BMI-blood pressure relationship, highlighting the contribution of prenatal factors to cardiovascular risk development. These findings extend current knowledge within the Developmental Origins of Health and Disease (DOHaD) framework by demonstrating interaction effects in childhood. Prenatal conditions may shape individual susceptibility to obesity-related increases in blood pressure. This study provides new insights that may contribute to pediatric cardiovascular risk assessment and early prevention strategies.