Pregnancy and birth complications in the unaffected siblings of patients with familial and nonfamilial schizophrenia

Abstract

Pregnancy and birth complications (PBCs) have emerged as a robust risk factor for the development of schizophrenia in adult life. However it is not clear whether PBCs represent an independent environmental cause of schizophrenia or whether they themselves are more likely in the presence of predisposing genes to schizophrenia, We sought to explore this issue further by comparing rates of PBCs in nonpsychotic subjects likely to be enriched and depleted for predisposing genes to schizophrenia using data from the Maudsley Family Study. PBCs were assessed by maternal interview using the Lewis-Murray scale on 52 unaffected siblings of patients with schizophrenia from multiply affected families, 47 unaffected siblings of patients with schizophrenia with no family history of psychosis and 130 controls with no personal or family history of psychotic disorder. The siblings were screened for absence of psychotic illness using the SADS-L or by maternal interview using the FIGS. Eleven (21.2%) siblings of familial schizophrenic patients and 11 (23.4%) siblings of sporadic schizophrenic patients had definite obstetric complications. Neither the siblings of familial schizophrenic patients (OR=0.82, 95% CI: 0.38-1.80) nor the siblings of nonfamilial schizophrenic patients (OR = 1.24, 95% CI: 0.57 2.70) differed significantly from controls with regard to their rate of PBCs. This argues against schizophrenia genes predisposing to PBCs and is consistent with other studies which found no increased rate of PBCs in the siblings or offspring of subjects with schizophrenia when compared with control groups.