Maternal metal intake during pregnancy and childhood behavioral problems in Japan: the Kyushu Okinawa Maternal and Child Health Study

Objectives: Lower maternal metal intake during pregnancy might affect childhood development. The current prebirth cohort study investigated the relationship between maternal intake of zinc, magnesium, iron, copper, and manganese during pregnancy and behavioral problems in Japanese children aged five years. Methods: Subjects were 1199 mother–child pairs. Dietary intake during the preceding month was assessed using a diet history questionnaire. Emotional, conduct, hyperactivity, and peer problems and low prosocial behavior were assessed using the Strengths and Difficulties Questionnaire. Maternal age, gestation at baseline, region of residence, number of children, maternal and paternal education, household income, maternal depressive symptoms during pregnancy, maternal alcohol intake during pregnancy, maternal smoking during pregnancy, child’s birth weight, child’s sex, breastfeeding duration, smoking in the household during the first year of life, and some dietary confounders that were associated with outcomes under study in this population were adjusted for. Results: Compared with maternal magnesium intake during pregnancy in the first quartile, magnesium intake in the second, third, and fourth quartiles was independently inversely related to childhood hyperactivity problems, but not to emotional, conduct, or peer problems or low prosocial behavior: the adjusted odds ratio between extreme quartiles was 0.48 (95% confidence interval: 0.23−0.99, P for trend = 0.04). No evident associations were observed between maternal intake of zinc, iron, copper, or manganese during pregnancy and childhood emotional, conduct, hyperactivity, or peer problems or low prosocial behavior. Conclusions: The present study suggests that higher maternal magnesium intake during pregnancy is inversely associated with hyperactivity problems in Japanese children.