Preconception folate and vitamin B6 status and clinical spontaneous abortion in Chinese women

OBJECTIVE: To assess the association between preconception homocysteine and B vitamin status and risk of clinical spontaneous abortion in women from Anqing, China. METHODS: All women were aged 21–34 years, had never smoked, and were primigravid. Patients ( n = 49) were women with a clinically recognized pregnancy who experienced a fetal death before 100 days’ gestation. Controls ( n = 409) were women who maintained a pregnancy that ended in a live birth. Homocysteine, folate, and vitamins B 6 and B 12 concentrations were measured in plasma obtained before conception. RESULTS: Mean vitamin B 6 concentration was lower in patients than in controls (34.0 versus 37.9 nmol/L, P = .04). In addition, the risk of spontaneous abortion tended to increase with decreasing plasma vitamin B 6 and folate concentration ( P for trend = .06 and .07, respectively), although the significance of these trends was further reduced in logistic models that included age, body mass index, and both vitamins. The risk of spontaneous abortion was four-fold higher among women with suboptimal plasma concentrations of both folate and vitamin B 6 (folate less than or equal to 8.4 nmol/L and vitamin B 6 less than or equal to 49 nmol/L) than in those with higher plasma concentrations of both vitamins (odds ratio 4.1, 95% confidence interval 1.2, 14.4). Homocysteine and vitamin B 12 status were not associated with spontaneous abortion risk. CONCLUSION: Suboptimal preconception folate and vitamin B 6 status, especially when they occur together, may increase the risk of clinical spontaneous abortion. Additional prospective studies are needed to confirm these findings and to determine whether antenatal B vitamin supplementation reduces spontaneous abortion risk.