Seasonality of schizophrenic births in Ireland.

The seasonality of births was examined for 4,855 schizophrenic patients born in Ireland between 1921 and 1955. All general births for the same years were used as controls. Schizophrenic births were found to be significantly elevated in the second quarter of the year (P less than .001). The excess was 11 per cent higher than for any European country examined to date.