Risks and benefits of nutritional supplements during pregnancy.

This review emphasizes the role of minerals and vitamins in pregnancy. Of the trace elements, iron, copper, zinc, and iodine have a fundamental role in human nutrition. Supplementation of iron, zinc, and iodine in the diet of all pregnant women, when dietary deficiencies exist, seems justified. The average diet in developed countries contains sufficient amounts of various vitamins, with the exception of folic acid, which may require supplementation. However, in developing nations and among poor populations in which the diet is inadequate, additional supplies of micronutrients are advisable.