Exposure to obstetric complications and subsequent development of bipolar disorder: Systematic review.

BACKGROUND Research has suggested an association between obstetric complications and bipolar disorder. However, no quantitative evaluation has been made of the pooled data from existing studies. AIMS To systematically review studies comparing exposure to obstetric complications in cases of bipolar disorder v. non-psychiatric controls, and in cases of bipolar disorder v. cases of other mental disorders. METHOD Publications were identified by computer searches of seven databases, by hand searches of reference lists and from raw data received from researchers. RESULTS Forty-six studies were identified, of which 22 met the inclusion criteria. The pooled odds ratio for exposure to obstetric complications and subsequent development of bipolar disorder was 1.01 (95% CI 0.76-1.35) compared with healthy controls, 1.13 (95% CI 0.64-1.99) compared with cases of unipolar disorder and 0.61 (95% CI 0.39-0.95) compared with those who developed schizophrenia. CONCLUSIONS There is no robust evidence that exposure to obstetric complications increases the risk of developing bipolar disorder. However, the range of events regarded as obstetric complications and methodological inadequacies make definitive conclusions difficult.