Obstetric complications as antecedents of schizophrenia: empirical effects of using different obstetric complication scales.

The new McNeil-Sjöström Scale for obstetric complications (OCs), as well as scales of Lewis et al. (Schizophrenia: Scientific progress. Oxford University Press, 1989) and Parnas et al. (British Journal of Psychiatry, 140, 416-420, 1982), were applied to the OC histories of 70 singleton schizophrenics and 70 demographically-matched controls from the same hospital delivery series, using blindly assessed hospital pregnancy and birth record information. With the McNeil-Sjöström scale, schizophrenics were found to have significantly increased rates of OCs for the total reproduction, as well as for labor-delivery and the neonatal period but not for pregnancy. Significant increases in OCs in these schizophrenics were also found in scores produced by the Lewis et al. scale but not by the Parnas et al. scale. Further application of these three scales to OC data obtained through parental report for 23 monozygotic (MZ) twin pairs discordant and 10 pairs concordant for schizophrenia, as well as seven normal control MZ pairs, showed a significant difference in OC rates across the different twin pair groups, when assessed by the McNeil-Sjöström and Parnas et al. scales, but not by the Lewis et al. scale. The particular scoring system used in a study is thus of considerable importance not only for findings concerning OC histories of schizophrenics vs. controls, but also for the relationship between OCs and other presumed etiological factors in schizophrenia. Among the three scales, the McNeil-Sjöström scale provided the most sensitive assessment of OC history for schizophrenics.