Seasonal variation of births in Greece. Temporal changes and regional differences over a 24-year period.

The seasonal variation of birth rates in Greece was studied for the years 1956-1979. The relatively constant pattern of the period 1956-1974 (with peak in January and February) turned abruptly into a new one (peak in May-July) for the following years. Whereas the seasonal variation of the first period could be explained as an effect of sociocultural (religious) factors on the rate of conceptions, no explanation was found for its change or for the new pattern. Regional differences between NW and SE Greece were also studied. Seasonal factors and their changes were almost similar in both regions.