Anencephaly in the United States, 1968-1987: the declining incidence among white infants.

The ethical issues concerning the use of fetal tissue as a source for organ transplantation has focused interest on anencephaly. For reasons that are not entirely clear, the incidence of anencephaly has been declining. As anencephaly is easily recognized and invariably fatal, mortality figures provide an excellent reflection of incidence. In the United States, between 1968 and 1987, infant mortality rates per 100,000 live births due to anencephaly declined from 22.4 to 12.1 (46.0%) for male infants and from 32.7 to 16.6 (49.2%) for female infants. However, when separated by race, the mortality rate declined for white male infants from 25.0 to 13.3 (46.8%) but only decreased from 9.0 to 7.7 (14.4%) for nonwhite male infants. The mortality rate declined for white female infants from 36.7 to 17.6 (52.0%) and actually increased slightly from 12.8 to 13.2 (3.1%) for nonwhite female infants. Thus, the declining incidence of anencephaly reflects a declining incidence of affected white infants but not of affected nonwhite infants.