engleski

High incidence rate of Down's syndrome livebirths to younger mothers in EUROCAT Registry 21 Zagreb, Yugoslavia

Registration of congenital anomalies began in January 1983 in the cities of Varaždin and Rijeka, and in 1986 it was extended to the regions of Koprivnica na Istra. The EUROCAT Central Registry reported a significantly higher incidence of Down syndrome (DS) in 1986 compared to previous years and an unusually high rate among mothers less than 30 years old. In 1987-1988 we still registered a high incidence of DS. Maternal age distribution was estimated. In this study, we sought to establish whether the high incidence of DS in 1986-1988 and the higher proportion of younger mothers was real or only due to methodological artefacts. Based on the data of the institute for Health Statistics, Republic of Croatia, the distribution of mother's age (in five-year intervals) for the whole period was performed. In the Zagreb registry 81.3% of mothers were less than 30 years old. There were no significant variations in age distribution from 1983 to 1988. Among 31 328 newborns, there were 54 registered cases of DS, and in 50 cases diagnosis was confirmed by karyotype. Compared with other EUROCAT centers, Center 21 Zagreb has a higher proportion of mothers younger than 30 years (EUROCAT centers:54.2-80.7%) with the highest incidence of DS (EUROCAT centers: 5.7-7.3 per 10 000 livebirths): Time clustering of DS in 1986- 1988 was a methodological artefact, a consequence of the inclusion of new regions in the Registry. Although the reasons for the incidence variation are unknown, it seems likely that exogenous factors are partially responsible. Further investigations are in progress. Detection of chromosomal aberrations in children born to younger mothers as well as the elucidation of the etiology and prevention of nondisjunction continue to be significant, not easily solved problems.

EUROCAT ; epidemiology ; congenital anomalies ; Croatia ; Down syndrome

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