Sociodemographic patterns in spina bifida birth prevalence trends--North Carolina, 1995-1999.

Previous studies have documented a decline in neural tube defects (NTDs) in the United States after the addition of folic acid to enriched grain products and other folic acid initiatives. The decrease generally has been greater for spina bifida than for other NTDs. However, the extent to which the decline varies by maternal sociodemographic characteristics has not been examined. In this study data from the North Carolina Birth Defects Monitoring Program, a statewide, population-based birth defect surveillance program, were used to assess the impact that folic acid public health initiatives have had on spina bifida rates among various sociodemographic subpopulations in North Carolina. This report covers data from 1995 through 1999. The overall prevalence of spina bifida decreased by 27.2% during 1995-1996 and 1998-1999 (p = 0.014). The magnitude of the decline varied considerably by sociodemographic characteristics of the mother. The decline was greatest among mothers who were aged > or = 30 years (prevalence ratio [PR] = 0.53), who had more than a high school education (PR = 0.57), whose prenatal care was not paid by Medicaid (PR = 0.67), and who were non-Hispanic white (PR = 0.72). Geographically the decrease in the western and Piedmont regions of the state was almost threefold that occurring in the eastern region. The decline in spina bifida after fortification varied considerably by sociodemographic subpopulations. More effort is needed to target folic acid education programs at disadvantaged populations.