PITTSBURGH—Vitamin D deficiency was associated with bacterial vaginosis (BV) and may contribute to the strong racial disparity in the prevalence of BV, according to a study conducted at the University of Pittsburgh Graduate School of Public Health (J Nutr. 2009). Women (n=469) enrolled in a pregnancy cohort study at less than 16 weeks, underwent a pelvic examination and provided a blood sample for determination of serum 25-hydroxyvitamin D [25(OH)D]. Approximately 41 percent of women had BV and 52 percent had a serum 25(OH)D concentration less than 37.5 nmol/L. The mean unadjusted serum 25(OH)D concentration was lower among BV cases compared with women with normal vaginal flora. BV prevalence decreased as vitamin D status improved (P<0.001). Approximately 57 percent of the women with a serum 25(OH)D concentration less than 20 nmol/L had BV compared with 23 percent of women with a serum 25(OH)D concentration more than 80 nmol/L. There was a dose-response association between 25(OH)D and the prevalence of BV. The prevalence declined as 25(OH)D increased to 80 nmol/L, then reached a plateau. Compared with a serum 25(OH)D concentration of 75 nmol/L, there were 1.65-fold and 1.26-fold increases in the prevalence of BV associated with a serum 25(OH)D concentration of 20 and 50 nmol/L, respectively, after adjustment for race and sexually transmitted diseases.