Epidemic waves in the prevalence of anencephaly and spina bifida in New York State

This study examines the prevalence of anencephaly and spina bifida among births in New York State from 1945 through 1971. The data suggest that the regression of the epidemic that peaked in the early 1930s may be continuing. The apparent leveling of the rate during the 1950s may have been another of the epidemic waves or peaks that have occurred in the last 70 years.