ABSTRACT
Neural tube defect [NTD] is the second common congenital disorder after cardiac disease. The most prevalent forms are anencephaly and spina bifida. Many factors are involved in this anomaly. Recent studies suggest environmental parameters as well as genetic factors. This descriptive study was conducted to determine the incidence of neural tube defect and its influencing factors in neonates at teaching hospitals of Tehran. Neonates at five hospitals were assessed during three years. Of 38473 reported births, 143 cases had neural tube defect. 11.9% of their mothers had previous medical conditions such as diabetes mellitus, epilepsy, psychiatric problems and cardiac disorders. 5.6% of mothers had preeclampsia during their pregnancy. NTD occurs during 28 days after conception. Since many conceptions are unplanned, it can be prevented by continuous consumption of folic acid over reproductive years