These two authors contributed equally.
Birth seasonality in schizophrenia: Effects of gender and income status
Article first published online: 2 SEP 2013
© 2013 The Authors. Psychiatry and Clinical Neurosciences © 2013 Japanese Society of Psychiatry and Neurology
Psychiatry and Clinical Neurosciences
Volume 67, Issue 6, pages 426–433, September 2013
How to Cite
Cheng, C., Loh, E.-W., Lin, C.-H., Chan, C.-H. and Lan, T.-H. (2013), Birth seasonality in schizophrenia: Effects of gender and income status. Psychiatry and Clinical Neurosciences, 67: 426–433. doi: 10.1111/pcn.12076
- Issue published online: 2 SEP 2013
- Article first published online: 2 SEP 2013
- Manuscript Accepted: 25 JAN 2013
- Manuscript Revised: 10 DEC 2012
- Manuscript Received: 14 AUG 2012
- Taichung Veteran General Hospital. Grant Number: TCVGH-100-3105
- season of birth;
The aim of this study was to examine the correlations of birth seasonality in schizophrenia, considering influences of gender and income status.
The sample consisted of 1 000 000 people in the general population randomly selected from the Taiwan National Health Insurance Research Database. Data for the birth-year period 1950–1989 were extracted for analysis (n = 631 911; 306 194 male, 325 717 female). Subjects with schizophrenia (2796 male, 2251 female) were compared with the general population. Subgroups divided by birth-year periods (10-year interval), gender, and income status (low, medium, high) were analyzed using both the Walter and Elwood seasonality and chi-squared tests.
The winter/spring birth excess in schizophrenia was 5.3% when compared with the general population. There was a statistically significant excess in winter/spring births than summer/autumn births inschizophrenia patients (relative risk [RR], 1.12; 95% confidence interval [CI]: 1.06–1.18). This winter/spring birth excess in schizophrenia was observed only in female subjects (RR, 1.20; 95%CI: 1.10–1.30), not in male subjects (RR, 1.03; 95%CI: 0.98–1.14), in all subgroups of income status, but was most pronounced in the low income subgroup (RR, 1.20, 1.09, 1.13; 95% CI: 1.05-1.37, 1.01–1.17, 1.02–1.25 for low, medium, and high income status, respectively).
A gender difference with female predominance of the effect of birth seasonality in schizophrenia, and a more pronounced effect in low income status were noted.