Prenatal illness and subtypes of schizophrenia: The winter pregnancy phenomenon

Seasonality of birth patterns is examined among a sample of 801 patients wi th schizophrenia separated into Type I and Type II schizophrenia. Findings indicate that both groups of patients were in utero during the winter but d uring different trimesters. Patients with Type I schizophrenia were more li kely to be in utero during the third trimester. Patients with Type ii schiz ophrenia were more likely to have been in the womb during the first trimest er. Implications for fetal brain development are discussed. (C) 1999 John W iley & Sons, Inc.