Obstetric complications in histories of monozygotic twins discordant and concordant for schizophrenia.

Histories of obstetric complications (OCs) during pregnancy, labor-delivery and the neonatal period were investigated by detailed maternal report for 23 monozygotic (MZ) twin pairs discordant for schizophrenia, 10 MZ twin pairs concordant for schizophrenia and 7 normal MZ control pairs. Statistically significant differences in OC rates were found across these 3 groups. OCs being most frequent in discordant pairs and least frequent in normal control pairs. Labor complications were significantly more frequent in discordant than concordant pairs. OC rates were equivalent in sick and well discordant twins. The results provide evidence for the role of OCs in the development of schizophrenia, complications at the time of birth being especially associated with the development of schizophrenia in discordant twins.