Spina bifida and anencephaly are the two most common neural tube defects (NTDs) in the United States, affecting approximately 4000 pregnancies each year. In the past decade, randomized controlled trials have demonstrated that folic acid supplementation prior to conception and during the first trimester of pregnancy reduce the recurrence of NTDs by 72% in women with a previous NTD-affected pregnancy. Other research has shown that supplementation reduced the occurrence of NTDs by 100%. In 1992, the US Public Health Service recommended that all US women of reproductive age should consume 400 [micro]g of folic acid daily. Unfortunately, a survey conducted in 1998 demonstrated that only 29% of US women were following this recommendation. In light of these and similar statistics, the US Food and Drug Administration (FDA) authorized the addition of folic acid to enriched grain products in March of 1996 and made compliance by food manufacturers necessary by January of 1998. The fortification measure was to add approximately 100 [micro]g of folic acid to the daily diet of the average person and result in approximately 50% of all women of reproductive age receiving the recommended 400 [micro]g of folate daily from all sources.
In an attempt to determine the effects of this fortification effort, researchers utilized birth certificates of infants, which since 1989 include check boxes for selected congenital anomalies, including anencephaly and spina bifida. Through the use of birth certificates, investigators compared birth certificate reports of spina bifida and anencephaly before fortification (October 1995 through December 1996) with those after mandatory fortification (October 1998 through December 1999). This was a national study of birth certificate data for live births to women in 45 US states and Washington, DC.
From October 1995 through December 1996, spina bifida was found to occur in 26.2 per 100,000 births in the US while anencephaly was found in 11.6 per 100,000 births. The birth prevalence of spina bifida decreased to 20.2 per 100,000 births during October 1998 through December 1999, indicating a 23% decline. During the 1998-1999 period, the birth prevalence of anencephaly declined to 10.3 per 100,000 births representing an 11% decline.
Overall, a 19% reduction in NTD birth prevalence occurred following folic acid fortification of the US food supply. Factors other than fortification, including increased awareness and increased usage of prenatal vitamins, may also have contributed to this decline. However, it does appear that the fortification process has had a positive impact on the reduction of NTDs in the US. Further evaluation of the impact of folic acid fortification on the occurrence of NTDs is under way.
M. Honein, L. Paulozzi, T. Mathews, et al. Impact of folic acid fortification on the US food supply on the occurrence of neural tube defects. JAMA;285:2981-2986 (June 20, 2001) [Correspondence: Margaret A. Honein, PhD, MPH, National Center on Birth Defects and Developmental Disabilities, Mailstop F-45, Centers for Disease Control and Prevention, 4770 Buford Hwy. NE, Atlanta, GA 30341-3724. E-mail: Mhonein@cdc.gov].
COPYRIGHT 2001 Frost & Sullivan
COPYRIGHT 2001 Gale Group