Serum magnesium in women during pregnancy, while taking contraceptives, and after menopause

Mean serum magnesium values with one standard deviation are presented for 224 women during pregnancy and 1559 women taking birth control pills, with 4145 women, aged 15-49 years, as controls. In addition, similar data are presented for 2,884 women, aged 50-74 years, after menopause. All these women were surveyed in the first National Health and Nutrition Examination Survey in the United States of America, 1971-1974 (NHANES I). Information on use of birth control pills is based on two questions taken from the NHANES I medical history interview. Pregnant women had significantly lower serum magnesium values than controls (nonpregnant and no birth control pills), regardless of age or race. Women on the pill also showed significantly lower serum magnesium values than other nonpregnant women of similar age, but the differences were much smaller than those between pregnant women and controls. Women older than 50 years (postmenopausal women) had significantly higher serum magnesium values than premenopausal women. These findings are compared with similar findings from other studies in the United States and other parts of the world.