Month of birth, hemisphere of birth and schizophrenia

Background. To assess quarterly fluctuations in schizophrenia births in a southern hemisphere data set, and to compare the quarterly birth distributions of patients born in the northern and southern hemisphere. Method. The month and place of birth of patients with schizophrenia (n = 9348) were extracted from a mental health register. Results. The quarterly birth distribution of patients with schizophrenia differed significantly from the estimated general population distribution in SH-born patients. The quarterly distribution of patient births differed significantly when the two hemispheres were compared. Conclusion. These data support the hypothesis that there is a risk for schizophrenia that is related to the time of birth, and which fluctuates across the year.