Mental disorder and season of birth: comparison of psychoses with neurosis.
1. Seasonal distribution of birth has been examined for 3,596 schizophrenic, 5,672 manic-depressive and 14,076 neurotic patients attending a particular hospital during 1951-1963.

2. It is argued that in season-of-birth studies, the populations being compared should be matched for age as well as for social class, religion and birth-place. In the present study, the age-structure of the schizophrenic and neurotic groups were closely similar and widely different from that of the manic-depressive; but matching for birth-place was less satisfactory. [See Table V in Source Pdf.]

3. The findings indicate an excess of winter births in schizophrenic patients compared with neurotic patients.

4. Hypotheses which might account for this are considered.