Decline in the prevalence of spina bifida and anencephaly by race/ethnicity: 1995-2002

University of Alabama at Birmingham, Birmingham, Alabama, United States
PEDIATRICS (Impact Factor: 5.47). 10/2005; 116(3):580-6. DOI: 10.1542/peds.2005-0592
Source: PubMed


In an effort to reduce the occurrence of neural tube defects (NTDs), folic acid fortification of US enriched grain products was authorized by the Food and Drug Administration in March 1996 and required by January 1998. Fortification has been shown to result in an important decline in the prevalence of spina bifida and anencephaly in the general US population; however, fortification's impact on specific racial/ethnic groups has not been well described. We sought to characterize the decline in the prevalence of spina bifida and anencephaly among specific racial/ethnic groups during the transition to mandatory folic acid fortification in the United States.
Data from 21 population-based birth defects surveillance systems were used to examine trends in prevalence of spina bifida and anencephaly for specific racial/ethnic groups for the years 1995-2002. These years were divided into 3 periods: prefortification, optional fortification, and mandatory fortification. Race/ethnicity was defined as Hispanic, non-Hispanic white, and non-Hispanic black. Prevalence ratios were calculated for each racial/ethnic group by dividing the prevalence from the mandatory fortification period by the prevalence in the prefortification period.
The study included data on 4468 cases of spina bifida and 2625 cases of anencephaly. The prevalence of spina bifida and anencephaly was highest among Hispanic births, followed by non-Hispanic white births, with the lowest prevalence among non-Hispanic black births. Significant declines in spina bifida and anencephaly were observed among Hispanic births and non-Hispanic white births. The prevalence ratio for non-Hispanic black births was of borderline significance for spina bifida and was not significant for anencephaly.
The results of this study suggest that folic acid fortification is associated with significant decreases in the prevalence of spina bifida and anencephaly among non-Hispanic white and Hispanic births. The magnitude of the reduction was similar between these 2 groups and was more pronounced for spina bifida than for anencephaly. The decline in the prevalence of spina bifida and anencephaly among non-Hispanic black births did not reach statistical significance. Efforts to increase folic acid consumption for the prevention of NTDs in pregnancies among women of all races/ethnicities should be continued, and studies to identify and elucidate other risk factors for NTDs are warranted.

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    • "For this reason, iron and folic acid fortification of foods for mass consumption is considered an important strategy to increase micronutrient levels in the population. A number of countries have already opted to increase population folic acid intake through inexpensive, large-scale fortification, which has proven to be moderately effective and safe [43-57]. However, legislation for mandatory fortification of food staples has still not been enacted in many countries. "
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    • "In fact, a 19% reduction in NTD birth prevalence has been reported following FA fortification of the US food supply [27]. An analysis of US data by race showed that statistically significant decreases in the prevalence of NTDs during fortification in the US occurred among CA women (~32% decline), but not among AA women (~13% decline) [28]. Although it is possible that the remaining NTD-affected pregnancies in AA women are not responsive to FA and may be associated with low vitamin B12 [29] or other factors, it is also possible that AA women are not reaching NTD-protective concentrations of circulating folate and therefore require higher folate intakes to prevent NTDs. "
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    • "Our results are comparable with others [9,13,14,15] in describing an overall decline in NTD’s over time, especially after food fortification. Although we show that all the declines were sustained by women across all SES strata there was no significant narrowing of the gap between high and low income areas. "
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