Efficacy of vitamin D supplementation in gestational diabetes mellitus: Systematic review and meta-analysis of randomized trials

Abstract

BackgroundTrials have examined on the benefits of vitamin D supplementation in pregnant women.ObjectiveThis review aimed to evaluate whether oral vitamin D supplements, when given to pregnant women with gestational diabetes mellitus (GDM), would improve maternal and neonatal outcomes, compared with no treatment or placebo.MethodWe performed a systematic review following Cochrane methodology, and randomized trials were included where pregnant women with GDM received vitamin D supplementation versus placebo/no treatment or vitamin D and calcium versus placebo/no treatment. Primary outcomes were preeclampsia, preterm birth, cesarean delivery, gestational hypertension, and adverse events related to vitamin D supplementation. The search strategies were applied to the following databases: MEDLINE, Embase, LILACS, and CENTRAL. Similar outcomes in at least two trials were plotted using Review Manager 5.3 software. The quality of evidence was generated according to the Grading of Recommendations Assessment, Development, and Evaluation (GRADE).ResultsThe total of 1224 references were identified, eleven trials were potentially eligible, and six were included in this review (totaling 456 women). The meta-analysis of frequency of cesarean deliveries did not show significant differences between groups, none of the trials evaluated the remaining primary outcomes. For secondary outcomes, our results suggest that vitamin D supplementation in pregnant women with GDM may reduce newborn complications such as hyperbilirubinemia, polyhydramnios (RR: 0.40, 95% CI: 0.23 to 0.68; RR: 0.17, 95% CI: 0.03 to 0.89; respectively), and the need for maternal or infant hospitalization (RR: 0.13; 95% CI: 0.02 to 0.98; RR: 0.40, 95% CI: 0.23 to 0.69). However, the evidence was of low or very low quality.ConclusionWe did not find moderate or high quality evidence indicating that vitamin D supplementation, when compared with placebo, improves glucose metabolism, adverse maternal and neonatal outcomes related to GDM in pregnant women.

Vitamin D deficiency 2.0: an update on the current status worldwide

“…They suggested that vitamin D supplementation may reduce gestational diabetes, low birthweight, and preeclampsia, but a higher than currently recommended dose appeared to have no additional benefit except for possible further reduction of gestational diabetes [74,75]. However, several studies in recent years have highlighted that women are at high risk for vitamin D deficiency, and this is associated with adverse pregnancy outcomes, including preeclampsia and gestational diabetes [76][77][78][79][80]. It has been demonstrated that vitamin D supplementation is able to reduce adverse pregnancy outcomes when a higher level is achieved, with an increasing efficacy when the target level is raised from 20 to 40 ng/mL or 50 ng/mL.…”

Official recommendations for vitamin D through the life stages in developed countries

“…It is hypothesized that the role vitamin D plays in modulating immune function and preventing inflammation is the likely mechanism for which vitamin D supplementation in protecting maternal and fetal health [15]. Wagner et al have demonstrated that an intake of 4000 IU/d during pregnancy, to achieve a serum 25(OH)D above 40 ng/mL (100 nmol/L), can reduce the incidence of preterm by more than half [16] and may reduce other complications of pregnancy including preeclampsia, gestational diabetes and possibly post-partum hemorrhage [17][18][19]. Their findings have resulted in a vitamin D supplementation program (in place since 2017), wherein 5000 IU/d of vitamin D is provided to all pregnant women, implemented at five hospitals within the Medical University of South Carolina [20].…”

Large Retrospective Cohort Study of the Association Between Maternal 25-Hydroxyvitamin D Status and Birth Weight of Neonate

“…Varying blood collection periods and characteristics of the participants (the latter excluding preterm SGA infants) might have contributed to the differences in the study results. [17]. Moreover, a cohort study based on a prospective community research did not find any evidence showing that vitamin D status during early pregnancy was associated with pregnancy-related hypertension in women who did not have children [18].…”