Season of Birth in Patients with Schizophrenia in Thailand

Objective: An excess of schizophrenia births in the winter or spring is a well-known find-ing in Western studies; however, few studies from equatorial regions have been done. Our purpose is to investigate the seasonality of schizophrenia births in Thailand. Methods:This was a retrospective study in which patients with schizophrenia were identi-fied from computerized records at Thammasat University Hospital. The Edwards test was used to detect any birth seasonality patterns among the patients with schizophrenia. Subsequently, the data were compared against the general population birth month data to examine potential seasonal effects using the Walter-Elwood seasonality test. Results: There are 949 patients with schizophrenia, with a mean age of 39.3 years. The results demonstrate no evidence of distinctive seasonality in birth patterns among patients with schizophrenia (P = .329). The overall monthly distribution of births did not differ between the general population and patients with schizophrenia (P = .365). Conclusion: In Thailand, a tropical country, there does not appear to be an effect of season of birth and the later development of schizophrenia.