Neural Tube Defects and Maternal Folate Intake Among Pregnancies Conceived After Folic Acid Fortification in the United States

Abstract

Rates of neural tube defects have decreased since folic acid fortification of the food supply in the United States. The authors' objective was to evaluate the associations between neural tube defects and maternal folic acid intake among pregnancies conceived after fortification. This is a multicenter, case-control study that uses data from the National Birth Defects Prevention Study, 1998-2003. Logistic regression was used to compute crude and adjusted odds ratios between cases and controls assessing maternal periconceptional use of folic acid and intake of dietary folic acid. Among 180 anencephalic cases, 385 spina bifida cases, and 3, 963 controls, 21.1%, 25.2%, and 26.1%, respectively, reported periconceptional use of folic acid supplements. Periconceptional supplement use did not reduce the risk of having a pregnancy affected by a neural tube defect. Maternal intake of dietary folate was not significantly associated with neural tube defects. In this study conducted among pregnancies conceived after mandatory folic acid fortification, the authors found little evidence of an association between neural tube defects and maternal folic acid intake. A possible explanation is that folic acid fortification reduced the occurrence of folic acid-sensitive neural tube defects. Further investigation is warranted to possibly identify women who remain at increased risk of preventable neural tube defects.

Policy statement on folic acid and neural tube defects

“…Finally, it is possible that the postfortification NTDs are folate resistant and that further fortification will not be necessary. Mosley et al 41 did a case-control study in which cases and controls were sorted in quartiles in terms of folic acid supplementation use and dietary folate intake. There was no difference between cases and controls for any of the quartiles, suggesting that even at the lowest levels of intake, the amount of folic acid that was ingested was sufficient to prevent folate-sensitive NTDs.…”

Effect of increasing voluntary folic acid food fortification on dietary folate intakes and adequacy of reproductive-age women in New Zealand

“…This is important to consider because although many governments, including the New Zealand Government, recommend that reproductive-age women consume a daily supplemental intake of 400 mg folic acid in the periconceptional period, it is increasingly acknowledged that the level of folic acid required to prevent most folate-responsive NTD may be lower (26,27) . For example, the USA and Canada implemented mandatory fortification of enriched grain products in 1998.…”

Mothers of Children with Hydrocephalus: Aspects about Prenatal Care

“…The most frequent association reported in the literature is the nutritional deficit of vitamins and minerals as folic acid and zinc during pregnancy [3], [4]. The supplementation with folic acid prior to becoming pregnant and during pregnancy reduces the risk of neural tube defects [5].…”