VDR and gestational diabetes: The results showed that VDR gene rs7975232 polymorphism was associated with GDM significantly under the allelic model (OR = 1.28, 95% CI = 1.06–1.56), codominant model (CC vs. AA OR = 1.97, 95% CI = 1.28–3.05, P = 0.002), and recessive model (OR = 1.83, 95% CI = 1.27-2.64, p = 0.001) in the case of low heterogeneity.