Vitamin D insufficiency in pregnant and nonpregnant women of childbearing age in the United States

OBJECTIVE: We evaluated vitamin D insufficiency in a nationally representative sample of women and assessed the role of vitamin supplementation. STUDY DESIGN: We conducted secondary analysis of 928 pregnant and 5173 nonpregnant women aged 13-44 years from the National Health and Nutrition Examination Survey 2001-2006. RESULTS: The mean 25-hydroxyvitamin D (25[OH]D) level was 65 nmol/L for pregnant women and 59 nmol/L for nonpregnant women. The prevalence of 25(OH)D <75 nmol/L was 69% and 78%, respectively. Pregnant women in the first trimester had similar 25(OH)D levels as nonpregnant women (55 vs 59 nmol/L), despite a higher proportion taking vitamin D supplementation (61% vs 32%). However, first-trimester women had lower 25(OH)D levels than third-trimester women (80 nmol/L), likely from shorter duration of supplement use. CONCLUSION: Adolescent and adult women of childbearing age have a high prevalence of vitamin D insufficiency. Current prenatal multivitamins (400 IU vitamin D) helped to raise serum 25(OH) D levels, but higher doses and longer duration may be required.