OBJECTIVE:Whereas there are numerous reports in the literature relating the impact of maternal nutritional status on subsequent birth outcome, much less is known about the long-term impact on infant growth after birth. Therefore, we conducted a prospective cohort study to investigate the association of maternal micronutrient status (vitamins A, C and E, folate) and oxidative stress status in pregnancy with infant growth during the first year of life. DESIGN:Prospective cohort study. SETTING:Outpatient clinic of obstetrics, Ewha Womans University Hospital, Seoul, South Korea. SUBJECTS AND METHODS:Two groups were constructed for this study - the Ewha pregnancy cohort (n = 677) and the infant growth cohort comprising follow-up live newborns of all the recruited pregnant women (n = 317). Maternal serum vitamin and urinary oxidative stress levels were collected and infant weights and heights were measured at birth and at 6 and 12 months after birth. RESULTS:Division of the subjects into folate-deficient and normal groups revealed that infant weight and height at 0, 6 and 12 months were adversely affected by folate deficiency. High maternal vitamin C was associated with increased infant weight and height at birth and after birth. CONCLUSION:Our findings indicate the importance of preventing folate deficiency and supplementing vitamin C during pregnancy.