Total and Free 25-Hydroxy-Vitamin D and Bacterial Vaginosis in Pregnant African American Women

OBJECTIVE: This study sought to investigate associations between serum total and free 25(OH)D and bacterial vaginosis (BV) in early and later pregnancy among US black women to provide insight into the most clinically relevant measure of vitamin D status among pregnant black women with respect to risk for BV as well as insights into critical time points for measuring and/or addressing vitamin D status in pregnancy. METHODS: Data and biospecimens were derived from a subsample (N = 137) of women from the Emory University African American Vaginal, Oral, and Gut Microbiome in Pregnancy Cohort, for whom data related to vitamin D status (serum assays for total and free 25(OH)D) and Nugent score of Gram stained vaginal specimens in early (8-14 weeks) and later (24-30 weeks) were available. We compared total and free 25(OH)D concentrations for women according to Nugent score category (normal flora, intermediate flora, and BV) and assessed the odds of BV according to measures of vitamin D status. RESULTS: Thirty-seven (27%) women had adequate vitamin D status at baseline, whereas 70 (51%) had insufficient vitamin D and 30 (22%) were vitamin D deficient; there were not significant differences in the proportion of women with adequate, insufficient, or deficient vitamin D according to Nugent score category. However, the odds of BV later in pregnancy were significantly higher for women who experienced a smaller rise in total 25(OH)D and free 25(OH)D from 8-14 through 24-30 weeks gestation. CONCLUSION: The change in measures of vitamin D status from early to later pregnancy is associated with the occurrence of BV in pregnancy. Further research is needed to examine the association between the change in vitamin D status over pregnancy and the occurrence of BV and other measures of vaginal microbial composition as well as to identify factors that influence change in vitamin D status over pregnancy.