Vitamin D is associated with bioavailability of androgens in eumenorrheic women with prior pregnancy loss

Prior studies have reported mixed results regarding relationships between vitamin D, androgens, and sex hormone–binding globulin in patients with polycystic ovary syndrome. However, less is known regarding these associations in eumenorrheic, premenopausal women. Our objective was to study the relationships between serum vitamin D and androgen biomarkers in eumenorrheic women with a history of pregnancy loss who were attempting pregnancy. This was an analysis of a cohort of 1191 participants from the Effects of Aspirin in Gestation and Reproduction trial (2006–2012). Participants were attempting to conceive, aged 18–40 years, with 1–2 documented prior pregnancy losses and no history of infertility, and recruited from 4 academic medical centers in the United States. Serum vitamin D (25-hydroxyvitamin D) and hormone concentrations were measured at baseline. Vitamin D concentration was negatively associated with free androgen index (percentage change [95% confidence interval, –5% (–8% to –2%)] per 10 ng/mL increase) and positively associated with sex hormone–binding globulin (95% confidence interval, 4% [2–7%]), although not with total testosterone, free testosterone, or dehydroepiandrosterone sulfate after adjusting for age, body mass index, smoking status, race, income, education, physical activity, and season of blood draw. Overall, vitamin D was associated with sex hormone–binding globulin and free androgen index in eumenorrheic women with prior pregnancy loss, suggesting that vitamin D may play a role in the bioavailability of androgens in eumenorrheic women. We are limited in making assessments regarding directionality, given the cross-sectional nature of our study.