SEASON OF BIRTH AND OBSTETRICAL COMPLICATIONS IN SCHIZOPHRENICS

Many studies indicate that both obstetrical complications (OCs) and bi rth in winter or early spring are risk factors for schizophrenia, but few studies have examined how these risk factors covary in the same su bjects. We assessed pre- and perinatal OCs, while blind to diagnosis, using medical data recorded at the time of subjects' births, in 29 pro bands with DSM-III schizophrenia or schizoaffective disorder and 39 of their unaffected adult sibs. Pre- and perinatal OCs were both signifi cantly more common in probands than sibs. Schizophrenics not born duri ng the winter or early spring had significantly more total and perinat al OCs than schizophrenics born in other months, but did not differ fo r prenatal OCs. Results indicate that OCs increase risk for schizophre nia, but also suggest the possibility that the impact of OCs on this r isk may be affected by season of birth.