The mean dietary magnesium intake of pregnant women is 35-58% of the recommended dietary allowance of 450 mg. Low-income women consumed 97-100 mg magnesium/1,000 kcal while women with higher incomes averaged 120 mg/1,000 kcal. Diets high in fat and sugar and low in whole grains, vegetables and fruits have a lower magnesium density. Magnesium content of water can also make a significant contribution to magnesium intake. Magnesium from prenatal supplements, if present, is seldom more than 100 mg. Additional supplementation is needed for adequate magnesium nutriture during pregnancy.