Changing trend of neural tube defects in eastern Turkey.

STUDY OBJECTIVE The aim was to study the relationship between birth prevalence of neural tube defect (including anencephaly) in Eastern Turkey before and after the Chernobyl disaster. DESIGN This was a prospective study of time trends in live births and stillbirths over the years 1985-1990. Medical and sociodemographic data were recorded for the mothers. SETTING Elazig, Eastern Turkey. SUBJECTS There were 5240 live births and stillbirths during the study period, 24 of whom had neural tube defect and of these 20 had anencephaly. MAIN RESULTS Of the 5240 newborns, 24 had a neural tube defect, giving a birth prevalence of 4.5 per 1000 total births. Of these, 20 were anencephalic (3.8 per 1000). In all, of the 2355 conceptions estimated to have occurred prior to the Chernobyl disaster in May 1986, the birth prevalences of total neural tube defect and anencephaly were the same (1.7 per 1000). This contrasts with the years following after Chernobyl, when the birth prevalence of total neural tube defect was 6.9 per 1000 (5.5 per 1000 for anencephaly). The differences were statistically significant (p < 0.001). These two increased rates reached a peak of 12.4 (for total neural tube defects) and 8.9 (for anencephaly) in 1988. In 1989 the rate of total neural tube defects decreased to 10.0 and that of anencephaly to 8.6 per 1000. In 1990 the rate of total neural tube defects fell to 5.6 and that of anencephaly fell to 4.2. CONCLUSIONS The changes in birth prevalence of neural tube defects might be due to the Chernobyl disaster. However, the increases observed occurred mainly in infants conceived well over a year after the Chernobyl disaster, suggesting that other factors may be responsible.