Geographic distribution of anencephaly in the United States

The distribution of anencephaly mortality rates was calculated by county for the continental United States. The average annual anencephaly mortality rate for all races and both sexes, based on 1968-1978 data for the population under 5 years of age, was 5.1 per 100,000 per year. The average annual anencephaly death risk for 1970-1975 was 25.4 per 100,000 live births per year. The distribution of anencephaly mortality was confirmed by comparing maps of mortality data and annual death risk for the period 1970-1975.