Vitamin D supplementation to prevent Gestational Diabetes Mellitus: To improve offspring metabolic outcomes

Abstract

Background Gestational diabetes mellitus (GDM) affects between 4 and 20% of pregnancies globally. Children of women with GDM are more likely to be obese and both child and mother are at increased life-long risk of developing type 2 diabetes mellitus. There is an association between lower 25-hydroxyvitamin D concentration and glycaemia in both pregnant and nonpregnant populations. Vitamin D deficiency is common in pregnant women. It is not known whether vitamin D supplementation in pregnancy could prevent GDM. Aims To investigate whether vitamin D supplementation in pregnancy improves glycaemia and whether maternal vitamin D status is associated with long term metabolic outcomes in children. Methods Samples were analysed from two large pregnancy studies. The Screening for Pregnancy Endpoints (SCOPE) was an observational study with relevant samples available from 1710 participants. Serum samples collected at 14-16 weeks gestation were analysed 25-hydroxyvitamin D concentration by a LC-MS/MS method developed for this study. Associations were investigated between maternal vitamin D status at 15 weeks gestation and GDM later in pregnancy, offspring adiposity at 6 years of age as determined by percentage body fat and age-adjusted BMI z-score and maternal adiposity at 6 years followup. The Maternal Vitamin D Osteoporosis (MAVIDOS) study was a randomised placebo controlled trial of vitamin D supplementation in pregnancy. Relevant samples were available from 910 women. Fructosamine, a measure of mean plasma glucose, and metabolome profiling using GC-MS, were performed on plasma samples collected at 34 weeks gestation after 19 weeks of vitamin D supplementation. Results Vitamin D status at 15 weeks gestation was not associated with the development of GDM in SCOPE participants. Maternal vitamin D status was negatively associated with percentage body fat in children at 6 years and negatively associated with BMI change in mothers 6 years post-partum. Mean plasma fructosamine was not different between participants in the vitamin D supplementation and placebo groups of the MAVIDOS trial. 152 metabolites were detected by GC-MS. No individual metabolites were significantly different in relative abundance between the two groups; however fatty acids as a group were overall lower in relative abundance in the vitamin D intervention group. Conclusion Vitamin D status or supplementation in pregnancy was not associated with glycaemia later in pregnancy. Vitamin D status was negatively associated with measures of adiposity at 6 years follow-up in both mother and child and subtle changes in the plasma metabolome suggest vitamin D may have a small but real effect on metabolism.