Low birth weight and a family history of schizophrenia predict poor premorbid functioning in psychosis.

Risk factors thought to predispose to schizophrenia, and premorbid functioning, were assessed blind to diagnosis by interviewing the mothers of 73 patients with DSM-III schizophrenia or affective psychosis. Higher risk of schizophrenia in relatives, lower mean birth weight, a more frequent history of obstetric complications, and poorer educational achievement distinguished the patients with schizophrenia from those with affective psychosis. Low birth weight and obstetric complications each predicted childhood schizoid and schizotypal traits. Poor social adjustment between ages 5 and 11 was predicted by low birthweight and by a family history of schizophrenia.