Epidemiology of anencephaly in Texas, 1981-1986.

The incidence of anencephalic births among Texas residents for the period 1981 through 1986 is described. The annual incidence of this birth defect varied from 3.8 to 4.3 cases per 10,000 total births (live births and stillbirths). The highest mean annual incidence was found in East Texas and South Texas. Within all ethnic and racial groups studied, females had higher rates of anencephaly than males, and Spanish-surnamed residents had the highest incidence of this defect, with 5.0 cases per 10,000 live births. Mothers with three or more previous live births or a history of stillbirths were more likely to have anencephalic offspring than were those without these documented histories. Differences in the incidence of anencephalic births between Spanish-surnamed and non-Spanish-surnamed whites were not explained by differences in parity.