Maternal micronutrients and fetal outcome.

Maternal micronutrient deficiency has been related to adverse fetal effects. It is believed that micronutrient supplementation during pregnancy may improve fetal and neonatal outcome. Despite biological plausibility, the evidence base for individual micronutrient benefit on neonatal morbidity, mortality, growth and development is patchy and often contradictory, except for the role of folic acid in prevention of neural tube defects. Single micronutrient supplementation interventions have not been shown to consistently affect size at birth or duration of gestation. Sound evidence is generally lacking that micronutrient supplementation can reduce infection-related adverse pregnancy outcomes. However, preliminary data suggests that antenatal zinc supplements may cause reduction in later diarrheal and infectious morbidity in infants. The evidence linking maternal micronutrient deficiency to children's cognitive and motor functioning also lacks a clear consensus except for iodine in endemic areas. There is a pressing need for good quality randomized controlled trials evaluating food based and multiple micronutrient interventions in pregnancy and preconceptually. Future studies should also evaluate the effect on body composition and metabolism along with the functional consequences.