Trends in the postfortification prevalence of spina bifida and anencephaly in the United States.
BACKGROUND
The prevalence of NTDs in the US declined significantly after mandatory folic acid fortification; however, it is not known if the prevalence of NTDs has continued to decrease in recent years relative to the period immediately following the fortification mandate.


METHODS
Population-based data from 21 birth defects surveillance systems were used to examine trends in the birth prevalence of spina bifida and anencephaly during 1999-2000, 2001-2002, and 2003-2004. Prevalence data were stratified by non-Hispanic White, non-Hispanic Black, and Hispanic race or ethnicity. Prevalence ratios were calculated by dividing the birth prevalences during the later time periods (2001-2002 and 2003-2004) by the birth prevalences during 1999-2000.


RESULTS
During 1999-2004, 3,311 cases of spina bifida and 2,116 cases of anencephaly were reported. Hispanic infants had the highest prevalences of NTDs for all years. For all infants, the combined birth prevalences of spina bifida and anencephaly decreased 10% from the 1999-2000 period to the 2003-2004 period. The decline in spina bifida (3%) was not significant; however the decline in anencephaly (20%) was statistically significant.


CONCLUSIONS
While the prevalences of spina bifida and anencephaly in the United States have declined since folic acid fortification in the food supply began, these data suggest that reductions in the prevalence of anencephaly continued during 2001-2004 and that racial and ethnic and other disparities remain.
Boulet
Sheree L
SL
National Center on Birth Defects and Developmental Disabilities, CDC, Atlanta, Georgia 30333, USA. sboulet@cdc.gov
Yang
Quanhe
Q
Mai
Cara
C
Kirby
Russell S
RS
Collins
Julianne S
JS
Robbins
James M
JM
Meyer
Robert
R
Canfield
Mark A
MA
Mulinare
Joe
J
D000757:Anencephaly / Q000453:epidemiology* / Q000208:ethnology*; D044383:Black People / Q000706:statistics & numerical data; D005006:Ethnicity / Q000208:ethnology / Q000706:statistics & numerical data; D005492:Folic Acid / Q000494:pharmacology*; D005527:Food, Fortified; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D007231:Infant, Newborn; D011159:Population Surveillance; D015995:Prevalence; D016135:Spinal Dysraphism / Q000453:epidemiology* / Q000208:ethnology*; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data; D001741:Black or African American
D005492:Folic Acid