An unusual time pattern of central nervous

The occurrence of congenital anomalies varies between different countries ranging from 2-10% of births.1 Previous studies show that CNS congenital anomalies are the most prevalent type of anomalies in some areas.2-4 The aim of this study was to determine the time pattern, and to explore some clues to the etiology of CNS anomalies in Northwestern Iran. The study population comprised 158433 births (156627 live births and 1806 still births) in the area covered by the Public Health Center under the Tabriz University of Medical Sciences in Northwestern Iran. Every CNS anomaly diagnosed at birth/after in this geographically defined population of Northwestern Iran was included as a study subject. We were unable to include cases that died during pregnancy because there is no routine autopsy available in the regional medical facilities. A total of 960 children with CNS anomalies were identified and studied in the region between January 2000 through December 2007. The anomalies (including anencephaly, spina bifida, and hydrocephaly) were coded and classified according the International Classification of Diseases (ICD-10). For data analysis, we used descriptive statistics, simple regression analysis, epidemiologic indices, and 95 % confidence intervals (CI) using Microsoft Excel spreadsheet. There were no significant changes in the occurrenc