PRENATAL INFLUENZA INFECTIONS AND ADULT SCHIZOPHRENIA

We reported previously that residents of Greater Helsinki, Finland, wh ose mothers were exposed to the 1957 influenza epidemic during their s econd trimester of gestation had a significantly elevated risk of deve loping adult schizophrenia. The majority of the replication studies to date have not determined whether the mothers actually contracted an i nfection or the stage of gestation based on mother's last menstruation . We read prenatal clinic records of the mothers of the Helsinki-born schizophrenia subjects to determine timing of infection, as noted by t he prenatal clinic obstetric nurse at a time close to the actual infec tion. Schizophrenia subjects who were exposed in the second trimester had a significantly higher rate of definite influenza infection (86.7% ) in that period compared to those who were exposed during the first a nd third trimesters (20.0%). These results are interpreted with cautio n because of the small number of cases.