Birth order and schizophrenia

Abstract EN

Schizophrenia is an important disorder in psychiatry with an unknown etiology.

Many factors (e.g.

birth order) have been mentioned as its risk factor.

Since few studies with scientific designs on birth order and schizophrenia have been performed in Iran, this study was conducted. Every consecutive patient in psychiatric ward for 3 months was assessed and categorized according to the DSM-IV into four groups (i.e.

schizophrenia, schizoaffective and bipolar, major depressive disorder and others) and demographic characteristics (age, sex, birth order and family size) were evaluated. In comparison with the non-schizophrenic group, this study indicated that schizophrenia is more prevalent among the first-born children (P<0.01), even in schizophrenic group itself, the-born child was more commonly affected (P<0.001).

This result was independent from age, sex and family size.