In model 1, after controlling for age, BMI, AMH, type of infertility and causes of infertility, MTHFR 677CT (adjusted OR, 1.225; 95% CI, 1.087–1.380) and TT (adjusted OR, 1.355; 95% CI, 1.110–1.654) were positively associated with the risk of vitamin D deficiency compared with CC. The gene discussed is AMH; the disease is Infertility.