Improvements in the status of folate and cobalamin in pregnant Newfoundland women are consistent with observed reductions in the incidence of neural tube defects

Background: Historically, the province of Newfoundland and Labrador had one of the highest rates of neural tube defects (NTDs) in North America (1976-1991: 3.2/1000 births), which could be partially explained by the sub-optimal status of folate and cobalamin in this population. In order to gain evidence of the impact of folate fortification programs, as well as prenatal education programs, a cross-sectional study was conducted to obtain data on the folate and cobalamin status of pregnant Newfoundland women in the post-folate fortification era. Additionally, the rates of NTDs were determined. Methods: Blood samples were collected during the first prenatal clinic (at approximately 16 weeks gestation) from 365 pregnant women in Newfoundland in 2002. Samples were analyzed for serum folate, cobalamin and homocysteine. In addition, rates of neural tube defects were calculated from data collected from the Provincial Medical Genetics Program, Newfoundland. Data were compared to historical data from a similar population of pregnant women in Newfoundland. Results: The status of both folate and cobalamin has significantly improved (p < 0.0001) in the post-fortification era, concurrent with a significant reduction in the number of neural tube defects (NTDs), from 4.67 (years 1992-1996) to 1.01 (years 1998-2002) per 1000 total births. Interpretation: These data provide evidence that both folate and cobalamin status of pregnant Newfoundland women have improved since 1997. The data for cobalamin provide evidence that strategies in addition to folate fortification programs are contributing to the improvements of poor water-soluble vitamin status in this population, thus providing a partial explanation for the dramatic reductions in NTD rates observed since 1995.