To evaluate how prenatal exposure to antioxidant vitamins and heavy metals affects subsequent development. Maternal serum and cord serum levels of antioxidant vitamins (A, E, and C) were determined. Full-state, performance, and verbal intelligence quotients (FSIQ, PIQ, and VIQ, respectively) of 97 children were assessed at 5 years of age. The placental transport ratio (PTR: cord level relative to maternal serum level) of vitamin A (VA) was associated positively with FSIQ score (〞p〞=0.041), vitamin E (VE)-PTR was associated positively with PIQ (〞p〞=0.002) and FSIQ (〞p〞=0.025) scores, and cord serum cadmium (Cd) level was correlated negatively with VIQ score (〞p〞=0.025) at 5 years of age. High VE-PTR protected against low PIQ (OR=0.025; 〞p〞=0.021) and FSIQ (OR ≤0.001; 〞p〞=0.004). High maternal age was a protective factor against low VIQ (OR=0.661; 95% CI, 0.500-0.875; 〞p〞=0.004) and FSIQ (OR=0.700; 95% CI, 0.512-0.957; 〞p〞=0.025). A higher maternal education (OR=0.038; 95% CI, 0.003-0.458; 〞p〞=0.010) and economic level (OR=0.047; 95% CI, 0.004-0.579; 〞p〞=0.017) were protective against a low FSIQ score. VA-PTR predicted physical growth. VA-PTR and VE-PTR predicted intelligence test performance at 5 years old. High Cd in cord blood may negatively affect subsequent intelligence.