Vitamin D has been linked to antimüllerian hormone levels, suggesting a possible association with greater ovarian reserve, but large population-based studies are lacking. Our objective was to explore the association between vitamin D and follicle-stimulating hormone (FSH) in premenopausal women.
The Uterine Fibroid Study (1996-1999) enrolled randomly selected 30- to 49-year-old members of a Washington, DC, health plan (N = 1,430). Women provided blood and urine samples in addition to questionnaire data. The vitamin D metabolite 25-hydroxyvitamin D (25(OH)D) was measured in stored plasma samples. Urinary FSH (mIU/mg creatinine) was measured by immunofluorometric assay. To obtain baseline measures, we limited this investigation to urine samples collected in the first 5 days of the menstrual cycle or 5 days before menses onset. In addition, postmenopausal women and women using oral contraceptives were excluded, leaving 527 women for analysis. FSH was creatinine-adjusted, normalized by log transformation, and modeled with multivariable linear regression.
The median 25(OH)D level was 12 ng/mL, with approximately 75% of participants below the recommended level of 20 ng/mL. FSH and 25(OH)D were inversely related. For every 10-ng/mL increase in 25(OH)D, urinary FSH decreased by 14% (95% CI, −23 to −5; P = 0.003).
Vitamin D is inversely related to FSH. This is consistent with literature relating low vitamin D levels to lower antimüllerian hormone levels. Prospective studies should investigate whether low vitamin D levels contribute to decreased ovarian reserve.
From the 1Epidemiology Branch, National Institute of Environmental Health Sciences, Durham, NC; and 2Department of Obstetrics and Gynecology, University of North Carolina, Chapel Hill, NC.
Received February 20, 2014; revised and accepted June 25, 2014.
Funding/support: This research was supported, in part, by the Intramural Research Program of the National Institutes of Health National Institute of Environmental Health Sciences (Z01ES0490003).
Financial disclosure/conflicts of interest: None reported.
Address correspondence to: Anne Marie Z. Jukic, PhD, PO Box 12233, Durham, NC 27703. E-mail: email@example.com