Major congenital neurologic malformations. A 17-year survey.

We present characteristics of four major congenital neurologic malformations--anencephaly, spina bifida, encephaloceles, and hydrocephalus--from a population of 763, 364 live-born and still-born infants born from 1971 through 1987. During the 17-year study period, 275 infants had anencephaly (0.36 per 1000 total births), 526 had spina bifida (0.69 per 1000 total births), 112 had encephaloceles (0.15 per 1000 total births), and 370 had hydrocephalus (0.48 per 1000 total births). There was a female preponderance of infants with anencephaly, spina bifida, and encephaloceles, while males predominated among those with hydrocephalus. We found declining incidences of anencephaly, spina bifida, and encephaloceles only among white females. Black infants were significantly less likely than white infants or infants of other races to have spina bifida. Twenty percent of infants with anencephaly had congenital anomalies unrelated to the primary defect, as did 40% with encephaloceles, 37% with hydrocephalus, and 22% with spina bifida. Because the racial background of the patient population closely resembles that of the United States as a whole, the features of the malformations described may reflect those of the country.