Predicting the Impact of Folic Acid Fortification, Ready to Eat Cereals and Supplement Use on the Risk of Neural Tube Defects in the United States

Abstract

It has been reported that as RBC folate concentrations in women increase, the risk of having a neural tube defect (NTD)-affected pregnancy decreases and that this relationship is consistent between Chinese and Irish populations. We applied the Bayesian prediction model developed using data from the Chinese population to predict the risk of NTD affected pregnancies among U.S. women of childbearing age (12-49 years) using RBC folate concentration distributions from the 2007-2010 National Health and Nutrition Examination Survey. The overall predicted NTD risk was 6.9 per 10,000 births (95% uncertainty interval [UI] 5.0-9.0) based on a median RBC folate concentration of 1222nmol/L (σ =0.40). There was a moderate reduction in the predicted NTD prevalence between individuals who reported consumption of supplements containing folic acid compared to those who did not (3 NTDs per 10,000 births; 95% UI 0.8-5.2 NTDs; RBC folate concentration of 1557nmol [σ = 0.42] vs. 1134nmol/L [σ = 0.39]). Women reporting enriched cereal grain products (e.g. bread) as their only source of folic acid intake had a predicted elevated risk of NTD affected pregnancy (8.2 NTD per 10,000 births [95%UL 6.2-10.5]; median RBC folate concentration 1073nmol/L, σ = 0.36). Adding sources of folic acid (i.e. ready-to-eat cereals, supplements) was associated with increased RBC folate concentrations and predicted reduced NTD risk. Non-Hispanic white and Hispanic women had predicted NTD risks similar to that expected from published surveillance data (6.2 per 10,000 [95%UI 4.5- 8.2] and 7.2 per 10,000 [95%UI 5.3-9.3]);non-Hispanic black women had a predicted NTD risk (9.2 per 10,000; 95% UI 7.1-11.7) higher than expected. Further analyses are underway.