Abstract: Objective  To explore 5, 10-methylene tetrahydrofolate reductase(MTHFR) gene polymorphism and its relationship with vitamin B12(VitB12), homocysteine(Hcy) and folic acid(SFA) in women of childbearing age. 
Methods  In total, 124 cases of perinatal patients with adverse pregnancy history were included as group A, and another 124 perinatal women who underwent pregnancy examination in our hospital during the same period and had no history of adverse pregnancy were included as group B. After admission, 5, 10-MTHFR, methionine synthase reductase(MTRR) genes and serum VitB12, SFA and Hcy were detected in both groups. MTHFR(C677T, A1298C), MTRR(A66G) genotype and allele distribution were compared between two groups. Serum VitB12, Hcy and SFA levels were compared between two groups. Serum VitB12, Hcy and SFA levels of patients with different MTHFR C677T genotypes were compared. In addition, the correlation between serum VitB12, Hcy, SFA levels and MTHFR C677T genotype was analyzed. 
Results  The detection rate of MTHFR C677T genotype CT, TT and T allele distribution in group A was significantly higher than that in group B, with statistically significant differences(P＜0.05). There was no significant difference in genotype and allele distribution of MTHFR A1298C between two groups(P＞0.05). No significant difference was found in MTHFR A66G genotype and allele distribution between two groups(P＞0.05). The Hcy level of group A was significantly higher than that of group B, and the SFA level was significantly lower than that of group B, with statistically significant differences(P＜0.05). The Hcy levels of MTHFR C677T genotype CT and TT were higher than those of CC genotype, and the SFA level was significantly lower than that of CC genotype, with statistically significant differences(P＜0.05). Correlation analysis confirmed that serum Hcy level was positively correlated with MTHFR C677T genotype CT and TT type, and serum SFA level was negatively correlated with MTHFR C677T genotype CT and TT type(P＜0.05). 
Conclusion  There are SFA and Hcy fluctuations and MTHFR C677T gene mutations in women of childbearing age with previous adverse pregnancy history. Timely supplementation of SFA for WOMEN of childbearing age with MTHFR C677T genotype CT and TT may reduce the incidence of adverse pregnancy and improve pregnancy outcome.

Key words: fertile period, folic acid, vitamin B12, homocysteine