DefinitionPrevalence of spina bifida is the number of live-born infants with spina bifida but without anencephaly per 10,000 live-born infants. (Live-born infants are infants born with any evidence of life.)
NumeratorNumber of live-born infants with spina bifida (without anencephaly)
DenominatorNumber of live-born infants
Why Is This Important?Birth defects pose a significant public health problem. One in 33 babies is born with a structural birth defect in the United States. Birth defects are a leading cause of infant mortality and responsible for considerable morbidity with enormous economic and social costs.
In 1992, the U.S. Public Health Service recommended that women of childbearing age increase consumption of the vitamin folic acid to reduce the number of spina bifida and anencephaly cases in the United States. By 1998, <30% of women were following this recommendation. In 2001, researchers from CDC determined that the overall birth prevalence of these two neural tube defects declined 19% after mandatory folic acid fortification.
Healthy People Objective: MICH-28.1, Reduce the occurrence of spina bifidaU.S. Target: 30.8 live births and/or fetal deaths with spina bifida per 100,000 live births
Other ObjectivesCDC Environmental Public Health Tracking, Nationally Consistent Data and Measures (EPHT NCDM)
How Do We Compare With the U.S.?Before folic acid fortification, approximately 4,000 pregnancies resulted in 2,500--3,000 births in the United States each year affected by anencephaly or spina bifida.(http://www.cdc.gov/Mmwr/preview/mmwrhtml/00019479.htm)
During 1996--2001 in the US, a 23% decline occurred in neural tube defects (spina bifida and anencephaly combined). Spina bifida declined 24% during this period, and anencephaly declined 21%.
The US prevalence of spina bifida (without anencephaly) from 2004-2006 was 3.50 per 10,000 births. For more information, please see: http://www.cdc.gov/ncbddd/features/birthdefects-keyfindings.html
These data come from 14 birth defects surveillance programs: Arkansas, Arizona, California [8-county Central Valley], Colorado, Georgia [5-county metropolitan Atlanta], Illinois, Iowa, Kentucky, Massachusetts, North Carolina, Oklahoma, Puerto Rico, Texas, and Utah.
Due to variability in the methods used by state birth defects surveillance systems and differences in populations and risk factors, state prevalence estimates may not be directly comparable with national estimates or those of other states.