In terms of the risks for early spontaneous abortion, there was no multiplicative interaction between higher plasma HCY in early pregnancy, serum folate deficiency in early pregnancy, maternal MTHFR 677TT genotype and no folic acid supplementation during periconception (OR = 2.35, 95% CI: 0.39–14.09). The gene discussed is MTHFR; the disease is folate deficiency.