Which birth defect has declined since the United States began fortifying grains with folic acid (Vitamin B9)?

From the Guidelines

Neural tube defects have significantly declined since the United States began fortifying grains with folic acid (Vitamin B9) in 1998. This public health intervention has led to a reduction in neural tube defects, including spina bifida and anencephaly, as supported by the U.S. Preventive Services Task Force recommendation statement published in the Annals of Internal Medicine 1. Folic acid is crucial during early pregnancy, particularly in the first 28 days when the neural tube forms and closes to create the brain and spinal cord. The evidence indicates that most women in the United States are not ingesting fortified foods at a level thought to provide optimal benefit, highlighting the importance of supplementation with 0.4 mg (400 μg) of folic acid, as recommended by the U.S. Public Health Service in 1992 1.

Some key points to consider:

• Neural tube defects result from a malformation of the embryo's central nervous system and may result in serious birth defects like anencephaly or spina bifida.
• The Centers for Disease Control and Prevention estimates that the birth rates for neural tube defects, such as spina bifida and anencephaly, were 17.96 and 11.11 per 100 000 live births, respectively, in 2005.
• Two well-established risk factors for neural tube defects are a history of a fetus or child with a neural tube defect or having a first-, second-, or third-degree relative with such a defect.
• The prevalence of defects varies by ethnicity and race, with Hispanic and non-Hispanic white persons having higher rates of neural tube defects than black and Asian persons.
• Maternal medical conditions, such as diabetes and obesity, have also been associated with an increased risk of neural tube defects.

The CDC recommends that all women of childbearing age consume 400 micrograms of folic acid daily, either through fortified foods or supplements, to prevent these serious birth defects. This approach ensures protection even in unplanned pregnancies, as adequate folate levels must be present before conception and during early pregnancy to be most effective in preventing neural tube malformations, as supported by the study published in the Annals of Internal Medicine 1.

From the Research

Birth Defects Decline After Folic Acid Fortification

• The decline in birth defects after folic acid fortification in the United States is primarily observed in neural tube defects (NTDs), which include spina bifida and anencephaly 2, 3, 4, 5.
• Studies have shown that the mandatory fortification of cereal grain products with folic acid, which began in 1998, has led to a significant decline in the prevalence of NTDs 2, 3, 5.
• The estimated number of NTD-affected pregnancies in the United States declined from 4,000 in 1995-1996 to 3,000 in 1999-2000, highlighting the partial success of the U.S. folic acid fortification program 2.
• The birth prevalence of NTDs decreased by 19% after mandatory folic acid fortification, from 37.8 per 100,000 live births before fortification to 30.5 per 100,000 live births conceived after mandatory folic acid fortification 5.
• Specifically, the prevalence of spina bifida declined by 31% and the prevalence of anencephaly declined by 16% after mandatory fortification 2.

Types of Birth Defects Affected

• Spina bifida: a birth defect of the spine that can lead to varying degrees of impairment 2, 4.
• Anencephaly: a birth defect of the brain that can lead to death or severe disability 2, 4.
• Both spina bifida and anencephaly are types of neural tube defects that have declined in prevalence since the introduction of folic acid fortification in the United States 2, 3, 4, 5.