title: Obstetric complications and schizophrenia: historical and meta-analytic review.
abstract: OBJECTIVE
  This paper reviews the literature on obstetric complications as a risk factor for schizophrenia. The authors trace the evolution of this literature through different methods and carry out a quantitative review of the results from prospective, population-based studies.
  
  
  METHODS
  Relevant papers were identified by a MEDLINE search, by examination of reference lists of published papers, and through personal contact with researchers in the field. Studies were grouped in chronological order according to common themes or methods. Meta-analytic techniques were used to summarize the findings of prospective population-based studies.
  
  
  RESULTS
  The meta-analytic synthesis of the prospective population-based studies revealed that three groups of complications were significantly associated with schizophrenia: 1) complications of pregnancy (bleeding, diabetes, rhesus incompatibility, preeclampsia); 2) abnormal fetal growth and development: (low birthweight, congenital malformations, reduced head circumference), and 3) complications of delivery (uterine atony, asphyxia, emergency Cesarean section). Pooled estimates of effect sizes were generally less than 2.
  
  
  CONCLUSIONS
  Current methods of investigating the relationship between obstetric complications and schizophrenia are reaching the limit of their usefulness. Lack of statistical power to measure small and interactive effects and lack of detailed information about the prenatal period are major problems with current approaches. A combination of disciplines and approaches will be needed to elucidate the mechanisms underlying these small but important associations.
authors.affiliation: Division of Psychological Medicine P063, Institute of Psychiatry, De Crespigny Park, London SE5 8AF, UK. m.cannon@iop.kcl.ac.uk
authors.forename: Mary
authors.initials: M
authors.lastname: Cannon
authors.forename: Peter B
authors.initials: PB
authors.lastname: Jones
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
mesh_terms: D000293:Adolescent; D000328:Adult; D001720:Birth Injuries / Q000453:epidemiology; D016022:Case-Control Studies; D015897:Comorbidity; D036861:Delivery, Obstetric / Q000379:methods; D005260:Female; D049673:History, 20th Century; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D007744:Obstetric Labor Complications / Q000453:epidemiology / Q000266:history; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011446:Prospective Studies; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology / Q000209:etiology* / Q000266:history