Lower prenatal vitamin D status and postpartum depressive symptomatology in African American women: Preliminary evidence for moderation by inflammatory cytokines.

Vitamin D deficiency and elevated pro-inflammatory cytokines have each been associated individually with postpartum depression (PPD). African American women are at increased risk for prenatal vitamin D deficiency, inflammation, and prenatal and postpartum depressive symptoms, but biological risk factors for PPD in this population have rarely been tested. This prospective study tested whether low prenatal vitamin D status (serum 25-hydroxyvitamin D, 25[OH]D) predicted PPD symptomatology in pregnant African American women and whether high levels of prenatal inflammatory cytokines interacted with low 25(OH)D in effects on PPD symptoms. Vitamin D status was measured in the first trimester in a sample of 91 African American pregnant women who had a second trimester blood sample assayed for inflammatory markers. Depressive symptoms were assessed at a postpartum visit. An inverse association between prenatal log 25(OH)D and PPD symptomatology approached significance (β = -0.209, p = 0.058), and interleukin-6 and IL-6/IL-10 ratio significantly moderated the effect. Among women with higher levels of inflammatory markers, lower prenatal log 25(OH)D was associated with significantly higher PPD symptoms (p < 0.05). These preliminary results are intriguing because, if replicable, easy translational opportunities, such as increasing vitamin D status in pregnant women with elevated pro-inflammatory cytokines, may reduce PPD symptoms.