Preconception B-vitamin and homocysteine status, conception, and early pregnancy loss

Maternal vitamin status contributes to clinical spontaneous abortion, but the role of B-vitamin and homocysteine status in subclinical early pregnancy loss is unknown. Three-hundred sixty-four textile workers from Anqing, China, who conceived at least once during prospective observation (1996-1998), provided daily urine specimens for up to 1 year, and urinary human chorionic gonadatropin was assayed to detect conception and early pregnancy loss. Homocysteine, folate, and vitamins B₆ and B₁₂ were measured in preconception plasma. Relative to women in the lowest quartile of vitamin B₆, those in the third and fourth quartiles had higher adjusted proportional hazard ratios of conception (hazard ratio (HR) = 2.2, 95% confidence interval (CI): 1.3, 3.4; HR = 1.6, 95% CI: 1.1, 2.3, respectively), and the adjusted odds ratio for early pregnancy loss in conceptive cycles was lower in the fourth quartile (odds ratio = 0.5, 95% CI: 0.3, 1.0). Women with sufficient vitamin B₆ had a higher adjusted hazard ratio of conception (HR = 1.4, 95% CI: 1.1, 1.9) and a lower adjusted odds ratio of early pregnancy loss in conceptive cycles (odds ratio = 0.7, 95% CI: 0.4, 1.1) than did women with vitamin B₆ deficiency. Poor vitamin B₆ status appears to decrease the probability of conception and to contribute to the risk of early pregnancy loss in this population.