Risk for obstetric complications and schizophrenia

The goal of this study was to determine whether cases with schizophrenia or related disorders show a history of obstetric complications significantly more often than control subjects and, if so, whether the enhanced risk of a negative pregnancy outcome also extends to the non-schizophrenic offspring of cases. Data based on the obstetric birth case-notes of patients with diagnosed schizophrenia or related disorders were compared to those of normal 'healthy' control subjects; each case/control pair was individually matched by gender, time and parity of birth, maternal age and marital status. Forty-four case/control pairs born in Padova (Italy) between 1964 and 1978 were assessed for prenatal and perinatal complications, including abnormal gestational age or birthweight. No significant differences were observed between cases and control subjects in the general characteristics of birth; gestational age and birthweight in particular were strictly comparable between cases and control subjects. The schizophrenia spectrum patients (75%) were more likely than control subjects (59%) to have experienced at least one definite obstetric complication: odds ratio=2.07 (95% CI: 0.83-5. 15). Cases also suffered more complications per birth than control subjects (average 2:1). In particular, obstetric complications involving a clear damaging potential were seen significantly more often among cases than control subjects: 34% vs. 9%, Fisher's exact test, P=0.008 (odds ratio=5.17, 95% CI: 1.55-17.21). Moreover, severe obstetric complications were noted more often among males (n=13, 41%) than females (n=2, 15%). When any previous pregnancies of the mothers of patients were compared with those of the mothers of control subjects, mothers of cases were seen to have suffered unfavorable pregnancy outcomes significantly more often. In particular mothers of cases were seen to have had more miscarriages (OR=4.66), and pre-term births (OR=2.58) than control subects' mothers. Severe, brain-damaging obstetric complications would seem to be a possible antecedent to a diagnosis of schizophrenia or a related disorder in adulthood. Indeed, some early onset cases may be accounted for by prenatal brain lesions. This enhanced risk of negative pregnancy outcome may be under genetic control, contributing to the persistence of schizophrenia in the general population. The 'healthy' status of control subjects was ascertained indirectly, not by individual assessment of the subjects. The sample size limits the statistical power of calculations.