Maternal Serum B12 Levels and Risk for Neural Tube Defects in a Texas-Mexico Border Population

PURPOSE: Neural tube defects (NTDs) are common birth defects that can be prevented with folate fortification and supplementation. Studies suggest that other nutrients may also be essential to neural tube closure and have a potential role in risk reduction, with vitamin B12 mentioned most often. We determined the effect of maternal serum B12 levels, measured postpartum, on the risk of NTDs among a high risk Mexican American population. METHODS: The case-control study included 157 Mexican American women with NTD-affected pregnancies and 186 Mexican American women with normal pregnancies, who were residents of Texas-Mexico border counties and delivered during 1995 to 2000. RESULTS: Compared with women in the highest vitamin B12 quintile, women in the lowest quintile showed a strong risk effect (odds ratio (OR) = 3.0, confidence interval (CI): 1.4, 6.3); while those in the 2nd and 3rd quintiles showed moderate risk effects (OR = 1.6, CI = 0.7, 3.6 and OR = 1.7, CI = 0.8, 3.8, respectively). Adjusting for obesity, vitamin supplements, dietary folate, dietary B12, red blood cell folate, and other covariates did not materially change these estimates. CONCLUSIONS: Insufficient levels of serum B12, which are not normally indicative of a classical vitamin B12 deficiency nor stem from an inadequate diet, may be an important etiologic factor for NTDs in this population.