Schizophrenia and birth order in Pakistan

The paper describes a two stage study. In Stage I the birth orders of 453 adult patients with different diagnoses, seen in the routine work of a general hospital psychiatry department, were compared. Patients with schizophrenia had significantly higher average birth positions than patients with other diagnoses, even after controlling for sibship size.In Stage II, the birth positions of 64 patients with schizophrenia (DSMIIIR) were subjected to a goodness-of-fit chi-square test. Over-representation of eldest siblings was highly significant for both sexes. When patients aged 30 and above were analysed separately, there was still a significant excess of first-born. These findings are in contrast to birth order studies of schizophrenia in western populations. In the authors' opinion, they can not be accounted for by the biases to which birth order studies are prone. They indicate a need for further community-based studies.