Maternal serum vitamin B12, folate and homocysteine and the risk of neural tube defects in the offspring in a high-risk area of China.

OBJECTIVE To examine the association between the risk of neural tube defects (NTD) and maternal serum vitamin B12, folate and homocysteine in a high-risk area of China. DESIGN A case-control study was carried out in Luliang mountain area of Shanxi Province. SUBJECTS/SETTING A total of eighty-four NTD pregnancies and 110 matched controls were included in the study; their serum vitamin B12 and folate concentrations were measured by chemiluminescent immunoenzyme assay and total homocysteine concentrations by fluorescent polarisation immunoassay. RESULTS Serum vitamin B12 and folate concentrations were lower in NTD-affected pregnant women than in controls (P < 0.01). Serum total homocysteine was higher in the NTD group than in controls at less than 21 weeks of gestation (P < 0.01). Adjusted odds ratios revealed that women with lower vitamin B12 (adjusted OR=4.96; 95 % CI 1.94, 12.67) and folate (adjusted OR=3.23; 95 % CI 1.33, 7.85) concentrations had a higher risk of NTD compared to controls. Based on dietary analysis, less consumption of meat, egg or milk, fresh vegetables and fruit intake would increase the risk of NTD. CONCLUSIONS Lower serum concentrations of folate and vitamin B12 are related to the increased risk of NTD in high-risk populations. Both folate and vitamin B12 intake insufficiency could contribute to the increased risk of NTD. A dietary supplement, combining folate and vitamin B12, might be an effective measure to decrease the NTD incidence in these areas.