THE ROLE OF VITAMIN D SUPPLEMENTATION DURING PREGNANCY: META-ANALYSIS APPROACH

Abstract:Vitamin D inadequacy is highly prevalent among pregnant women worldwide. Inadequacy or deficiency of vitamin D can lead to adverse outcomes during pregnancy such as pre-eclampsia, gestational diabetes, and caesarian section. A systematic review and meta-analysis were conducted to examine the effectiveness of vitamin D supplementation on serum vitamin D status during pregnancy in randomized controlled trials (RCTs). A search was conducted in PubMed, Scopus, ProQuest, EBSCO, Cochrane CENTRAL Database of Controlled Clinical Trials, PsycINFO, CINAHL, and Google Scholar, in addition to searching reference lists in published reviews. A comprehensive list of RCTs of vitamin D status and supplemental use in pregnancy was compiled. The random effects model was used to determine a summary effect size using pre/post means and standard deviations of serum vitamin D levels from intervention and control groups. Sixteen RCTs indicated a large effect size (d = .849, 95% CI .607 – 1.001, p < .001). Serum vitamin D concentration at delivery was higher with vitamin D supplementation, and thereby the metabolic outlook was favorable for the mother and newborn. Heterogeneity of the meta-analysis was significant (Q = 344.418, p < .001); the I-squared statistic showed moderate heterogeneity (61.89%), which warranted subgroup analysis to identify possible sources of variation among the studies. Women who began vitamin D supplementation during the first trimester had a higher effect size and improved vitamin D status compared to those who began supplementation in the second or third trimester. Since pregnant women with vitamin D inadequacy or deficiency are more susceptible to complications, routine examination of vitamin D status should be conducted in pregnant women