Mediation of Pre-Pregnancy Body Mass Index and Dietary Patterns with Relation to Vitamin D and Erythropoiesis-Related Micronutrients in Pregnant Women.

Pre-pregnancy body mass index (BMI) and dietary patterns (DPs) have been linked to serum erythropoiesis-related micronutrients (iron, folate, and vitamin B12). We studied the mediating effects of pre-pregnancy BMI and DPs on the association of serum vitamin D with the levels of erythropoiesis-related micronutrients. A cross-sectional research involving 1485 pregnant women was carried out in hospitals and clinics between 2017 and 2019 using the Nationwide Nutrition and Health Survey in Taiwan. Dietary intake was measured using food frequency questionnaire, and DPs were identified utilizing principal component analysis. Serum vitamin D and iron biomarker levels were examined. A mediation analysis was conducted to investigate the mediating effects of pre-pregnancy BMI and DPs on the association of serum vitamin D levels with erythropoiesis-related micronutrient levels. Serum 25(OH) vitamin D was positively linked to erythropoiesis-related micronutrient levels. Pre-pregnancy BMI partially mediated the association between serum 25(OH) vitamin D and serum iron (indirect effect: -0.004, 95% confidence interval (CI): -0.009, 0.000), folate (indirect effect: -0.009, 95% CI: -0.021, 0.000), and vitamin B12 levels (indirect effect: -0.137, 95% CI: 0.282, -0.02). Animal and staple-based DP and mushrooms, roots, and dairy DP mediated the association between serum 25(OH) vitamin D and serum iron levels (indirect effect: -0.004, 95% CI: -0.009, 0.000 and indirect effect: -0.004, 95% CI: 0.009, 0.000, respectively). Pre-pregnancy BMI mediates the association of serum vitamin D with erythropoiesis-related micronutrients. Animal and staple-based DP and mushrooms, roots, and dairy DP mediate the association between serum vitamin D and iron status.