Placenta expression of vitamin D and related genes in pregnant women with gestational diabetes mellitus

•The expression of vitamin D related genes in the umbilical cord tissues of gestational diabetes has not been reported.•This study further explored the effect of vitamin D related genes on the fetus by studying the expression in the umbilical cord tissues of GDM.•This study investigated the effect of vitamin D related gene methylation on the pathogenesis of gestational diabetes.