Domain- and sex-specific effects of prenatal exposure to low levels of arsenic on children's development at 6 months of age: Findings from the Ma'anshan birth cohort study in China

The relationship between prenatal arsenic exposure at low levels and poor development in children, especially in regard to neurodevelopment, has aroused several concerns, but the conclusions have been inconsistent. It still remains unclear whether such adverse effect is associated with a specific profile of the developing brain in early life. To investigate the association between arsenic exposure in utero and children's development and behaviour, we performed a large prospective birth cohort study including 2315 mother-infant pairs in Anhui Province, China. The Ages and Stages Questionnaire of China (ASQ-C) was used to assess the status of children's development and behaviour at 6 months postpartum, and the levels of arsenic were determined in umbilical cord serum samples. Odds ratios for suspected developmental delay (SDD) in each domain of the ASQ-C clusters were estimated using logistic regression models. Compared with low arsenic levels group, medium and high arsenic levels were significantly associated with the increased risks of SDD in the personal-social domain among infants aged 6 months after adjustment for all potential confounders (OR = 1.33, 95% CI (1.01, 1.75) and OR = 1.47, 95% CI (1.08, 2.00), respectively). Sex stratification analysis demonstrated that this association was stronger in females. The sensitivity analyses also showed that high cord serum arsenic levels were associated with a 1.80-fold (95% CIs (1.12, 2.90)) higher risk of a more severe developmental delay in the personal-social domain among six-month-old females. Our results suggest that low-level arsenic exposure in utero could have an adverse domain-specific effect on children's development at 6 months of age, particularly among females. Further studies are warranted to support the findings and explore the mechanism of these domain-and sex-specific associations.