DO NORTH-AMERICAN WOMEN NEED SUPPLEMENTAL VITAMIN-D DURING PREGNANCY OR LACTATION

Studies in European and other countries have shown that vitamin D defi ciency during pregnancy may adversely affect fetal growth, bone ossifi cation, tooth enamel formation, and neonatal calcium homeostasis. Whet her effects of vitamin D deficiency on pregnant or lactating mothers d iffer from effects observed in nonpregnant or nonlactating women is no t clear. Poor maternal vitamin D status during lactation results in lo w breast-milk vitamin D. However, human milk usually contains small vi tamin D amounts and, under normal circumstances, the sunshine exposure of human-milk-fed infants is the major factor affecting their vitamin D status. Mothers at risk of vitamin D deficiency are those who avoid dairy products, which are routinely vitamin D fortified, and live in more northern latitudes. Dark-skinned women also are theoretically at risk of vitamin D deficiency. Sunshine exposure is a major vitamin D s ource, and given adequate exposure, supplemental vitamin D is not nece ssary. However, defining adequate sunshine exposure is difficult.