Vitamin D status is inversely associated with anemia and serum erythropoietin during pregnancy

ABSTRACTBackground: Vitamin D and iron deficiencies frequently co-exist.It is now appreciated that mechanistic interactions between iron andvitamin D metabolism may underlie these associations.Objective: We examined interrelations between iron and vitamin Dstatus and their regulatory hormones in pregnant adolescents, whoare a group at risk of both suboptimal vitamin D and suboptimaliron status.Design: The trial was a prospective longitudinal study of 158 pregnantadolescents (aged #18 y). Maternal circulating biomarkers ofvitamin D and iron were determined at midgestation (w25 wk) anddelivery (w40 wk). Linear regression was used to assess associationsbetween vitamin D and iron status indicators. Bivariate andmultivariate logistic regressions were used to generate the OR ofanemia as a function of vitamin D status. A mediation analysis wasperformed to examine direct and indirect relations between vitaminD status, hemoglobin, and erythropoietin in maternal serum.Results: Maternal 25-hydroxyvitamin D [25(OH)D] was positivelyassociated with maternal hemoglobin at both midgestation and atdelivery (P , 0.01 for both). After adjustment for age at enrollmentand race, the odds of anemia at delivery was 8 times greater inadolescents with delivery 25(OH)D concentrations ,50 nmol/L thanin those with 25(OH)D concentrations $50 nmol/L (P ,0.001).Maternal 25(OH)D was inversely associated with erythropoietin atboth midgestation (P ,0.05) and delivery (P ,0.001). The significantrelation observed between 25(OH)D and hemoglobin could beexplained by a direct relation between 25(OH)D and hemoglobin andan indirect relation that was mediated by erythropoietin.Conclusions: In this group of pregnant adolescents, suboptimal vitaminD status was associated with increased risk of iron insufficiency andvice versa. These findings emphasize the need for screening for multiplenutrient deficiencies during pregnancy and greater attention tooverlapping metabolic pathways when selecting prenatal supplementationregimens