Birth seasonality in schizophrenia: Effects of gender and income status

Chin Cheng, El Wui Loh, Ching Heng Lin, Chin Hong Chan, Tsuo Hung Lan

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Aims The aim of this study was to examine the correlations of birth seasonality in schizophrenia, considering influences of gender and income status. Methods 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. Results 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). Conclusion 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.

Original languageEnglish
Pages (from-to)426-433
Number of pages8
JournalPsychiatry and Clinical Neurosciences
Issue number6
Publication statusPublished - Sep 1 2013
Externally publishedYes



  • epidemiology
  • schizophrenia
  • season of birth
  • seasonality

ASJC Scopus subject areas

  • Neuroscience(all)
  • Neurology
  • Clinical Neurology
  • Psychiatry and Mental health

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