Ethanol-sensitive times for the human conceptus.

The world's literature has been scoured to obtain data on 492 examples of the fetal alcohol syndrome (FAS) in the Northern Hemisphere. The seasonally pattern of FAS birth prevalence rates is compared with the seasonality pattern of ethanol intakes to estimate the time-lag between them and hence the timing of ethanol damage during development. It is tentatively suggested, in the light of the data, that this timing might be as late as the 18th-20th week. If this can be substantiated, it would alloy opportunities for preventive measures to be feasible even during pregnancy. Seasonality data have never previously been used to estimate the timing of a sensitive period in prenatal development. The present estimate for ethanol is, however, tentative and should be regarded only as an interesting indicator for future studies.