Monitoring of Birth Defects and Epidemiology

A monitoring of birth defects based on systematic collection and accumulation of data in a defined population or selected hospitals using definite diagnostic criteria offers per se indispensable source of information for epidemiological studies such as retrospective case-control study or prospective cohort study. Each results of statistics or monitorings of birth defects currently conducted in Japan were briefly stated. The on-going investigation data on congenital malformations about over 1,524,700 births performed since 1972 by Japan Association for Maternal Welfare were reviewed. Osaka and Kanagawa Programs, population-based, have so far totally over 181,000 and 160,000 births resp. Factors increasing malformations suggested were stillbirth, low birth weight, small for gestational dates, consanguinity and smoking during pregnancy from Kanagawa Program. As an example of on-going international collaborative study by the members of ICBDMS, data have been collected on limb reduction deformities. However, it might be more standardized in various aspects. Three statistical techniques — Z-test, cusum test and sequential method were adapted to distinguish a significant increase from a baseline frequency or to identify significant temporal changes. Although abrupt fluctuations were encountered, overall patterns about 17 marker-defects revealed to be fairly stationary in these years. Collection of sufficient numbers of cases and controls or exposed and unexposed enough to detect significantly so far unknown complicated factors is not always easy. To clarify unknown factors (polygenic, multifactorial, synergism or spontaneous errors of development), co-work or co-ordinated study of epidemiology and experimental teratology would be desirable to fill the gap between them.