title: Prenatal and perinatal risk factors for schizophrenia, affective psychosis, and reactive psychosis of early onset: case-control study.
abstract: OBJECTIVE
  To examine prenatal and perinatal risk factors for subsequent development of schizophrenia and affective and reactive psychosis.
  
  
  METHODS
  Three population based, case-control studies conducted within a Sweden-wide cohort of all children born during 1973-9. This was done by linking individual data from the Swedish birth register, which represents 99% of all births in Sweden, to the Swedish inpatient register.
  
  
  METHODS
  Patients listed in inpatient register as having been first admitted to hospital aged 15-21 years with a main diagnosis of schizophrenia (n=167), affective psychosis (n=198), or reactive psychosis (n=292). For each case, five controls were selected.
  
  
  METHODS
  Risks of schizophrenia and affective and reactive psychosis in relation to pregnancy and perinatal characteristics.
  
  
  RESULTS
  Schizophrenia was positively associated with multiparity (odds ratio 2.0), maternal bleeding during pregnancy (odds ratio 3.5), and birth in late winter (odds ratio 1.4). Affective psychosis was associated with uterine atony (odds ratio 2.2) and late winter birth (odds ratio 1.5). Reactive psychosis was related to multiparity (odds ratio 2.1). An increased risk for schizophrenia was found in boys who were small for their gestational age at birth (odds ratio 3.2), who were number four or more in birth order (odds ratio 3.6), and whose mothers had had bleeding during late pregnancy (odds ratio 4.0).
  
  
  CONCLUSIONS
  A few specific pregnancy and perinatal factors were associated with the subsequent development of psychotic disorder, particularly schizophrenia, in early adult life. The association of small size for gestational age and bleeding during pregnancy with increased risk of early onset schizophrenia among males could reflect placental insufficiency.
authors.affiliation: Department of Neuroscience, Psychiatry, Ullerâker, University of Uppsala, S-750 17 Uppsala 17, Sweden. christina.hultman@ullpsyk.uu.se
authors.forename: C M
authors.initials: CM
authors.lastname: Hultman
authors.forename: P
authors.initials: P
authors.lastname: Sparén
authors.forename: N
authors.initials: N
authors.lastname: Takei
authors.forename: R M
authors.initials: RM
authors.lastname: Murray
authors.forename: S
authors.initials: S
authors.lastname: Cnattingius
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000453:epidemiology / Q000209:etiology*; D001724:Birth Weight; D016022:Case-Control Studies; D015331:Cohort Studies; D005260:Female; D006801:Humans; D010298:Parity; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D011618:Psychotic Disorders / Q000453:epidemiology / Q000209:etiology*; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology*; D012621:Seasons; D017678:Sex Distribution; D013548:Sweden / Q000453:epidemiology