The effects of vitamin D supplementation on glycemic control and maternal-neonatal outcomes in women with established gestational diabetes mellitus: A systematic review and meta-analysis

Background & aims: Gestational Diabetes Mellitus (GDM) is associated with a well-documented range of adverse pregnancy outcomes. The present meta-analysis was conducted to evaluate the effects of vitamin D supplementation on glycemic control and maternal-neonatal outcomes in women with established GDM.

Methods: Published literature was retrieved and screened from PubMed, Embase, Web of Science, CNKI (China National Knowledge Infrastructure), Wanfang, and Cochrane Center Register of Controlled Trails up to May 2020. RCTs of vitamin D supplementation on pregnant women with GDM were included.

Results: 19 RCTs (1550 participants) were eligible for meta-analyses. Overall, vitamin D supplementation significantly reduced serum fasting plasma glucose (FPG) (MD: -10.20 mg/dL, 95%CI: -13.43 to -6.96), insulin concentration (MD: -5.02 μIU/mL, 95%CI: -6.83 to -3.20) and the homeostasis model assessment of insulin resistance (HOMA-IR) (MD:-1.06, 95%CI: -1.40 to -0.72) in women with GDM. In addition, vitamin D supplementation in pregnant women with GDM significantly reduced adverse maternal outcomes including cesarean section (RR: 0.75, 95%CI: 0.63 to 0.89), maternal hospitalization (RR: 0.13, 95%CI: 0.02 to 0.98) and postpartum hemorrhage (RR: 0.47, 95%CI: 0.22 to 1.00). Several adverse neonatal complications including neonatal hyperbilirubinemia (RR: 0.47, 95%CI: 0.33 to 0.67), giant children (RR: 0.58, 95%CI: 0.38 to 0.89), polyhydramnios (RR: 0.42, 95% CI: 0.24 to 0.72), fetal distress (RR: 0.46, 95%CI: 0.24 to 0.90) and premature delivery (RR: 0.43, 95% CI: 0.26 to 0.72) were also significantly reduced.

Conclusions: This meta-analysis suggested that supplementation of GDM women with vitamin D may lead to an improvement in glycemic control and reduction of adverse maternal-neonatal outcomes.