Altered head size at birth is associated with maternal 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) exposure in Vietnamese infants

Infant body size at birth has been suggested as a good marker of fetal development. However, in Vietnam, impacts of maternal TCDD exposure originating from Agent Orane on body size indices at birth have not been investigated in infants from birth cohorts around former US airbases. We investigated the effects of maternal TCDD exposure and TEQ levels of dioxin congeners other than TCDD (non-TCDD) on body size indices at birth among 504 infants from three Vietnamese birth cohorts in two contaminated areas and one unexposed area. The effects of two exposure factors, TEQ-PCDD and TEQ-PCDF in breast milk were also analyzed. Two-way analysis of covariance was used to investigate associations between body size markers and exposure factors, including interaction between exposure factors after adjusting for confounders. In girls, maternal TCDD exposure was associated with increased head circumference at birth, suggesting larger fetal brain size. TCDD exposure also showed a risk of increased abdominal fat accumulation, indicated by larger abdominal circumference in girls, whereas higher TEQ-PCDFs exposure decreased abdominal size in both sexes, suggesting potential antagonistic effects between PCDF congeners and TCDD. These findings suggest that, in Vietnam, TCDD may be a specific dioxin congener to influence fetal growth and development leading to atypical neurodevelopment and abdominal obesity in a later life.