Anencephaly: thirteen years of epidemiological study in Pelotas city

The anencephaly is the most common lethal form among the CNS anomalies. Although isolated cases occur, the anencephaly seems to be caused by multiple factors. This malformation result from closure defects of the anterior neural sulk, during embryonic development. The aim of this study was analyze the frequency, etiology, and the risk factors of this congenital malformation. This population-based case-control study range all births occurred in five maternities of Pelotas city from January, 1st 1990 to December, 12 2002.