Maternal and Neonatal Metabolic Outcomes of Vitamin D Supplementation in Gestational Diabetes Mellitus: A Systematic Review and Meta-Analysis

INTRODUCTION: Many scientists have revealed the association between vitamin D deficiency and gestational diabetes mellitus (GDM). The purpose of this review was to evaluate the impact of vitamin D supplementation on maternal and neonatal health measures in GDM. METHODS: A comprehensive systematic literature search in the electronic databases including Cochrane Central Register of Controlled Trials, MEDLINE (PubMed), Scopus, Web of Sciences, EMBASE, Google Scholar, Clininaltrial.gov, and ProQuest as well as SID, Magiran, Irandoc, and Iranmedex for Persian literature review carried out up to January 2018. All RCTs and quasi-experimental studies that compared vitamin D supplementation with placebo or without supplementation on GDM women were included in this review. RESULTS: Five randomized controlled trials involving 310 women were included in the meta-analysis. There were significant differences in fasting Plasma Glucose (FPG; mean difference [MD] -12.54, 95% CI -15.03 to -10.05; 3 trials, 223 participants); total cholesterol (TC; MD -24.77, 95% CI -32.57 to -16.98; 3 trials, 223 participants); low-density lipoprotein (LDL) cholesterol (MD -18.92, 95% CI -24.97 to -12.88; 3 trials, 223 participants); high-density lipoprotein (HDL) cholesterol (MD, 3.87, 95% CI 1.20-6.55; 3 trials, 223 participants); high sensitivity C-reactive protein -(hs-CRP; MD -1.35, 95% CI -2.41 to -0.28; 2 trials, 126 participants); and Newborns' hyperbilirubinemia (OR 0.33, 95% CI 0.13-0.80; 2 trials, 129 participants). CONCLUSIONS: Supplementation of GDM women with vitamin D may lead to an improvement in FPG, TC, LDL, HDL, hs-CRP serum levels as well as in newborns' hyperbilirubinemia.