• Scientific Evidence
• Helpful actions - what can you do?

There is conflicting evidence regarding this risk factor. Some early studies (esp. Kinney 1993, 1998) found that individuals who developed bipolar disorder (as compared to their well siblings) experienced more obstetric complications at birth. This was based on mother recall and hospital records, both of which could be subject to error. Recall especially can be problematic, given the natural tendency to want to "explain away" a major illness. Some more recent studies (esp. Mortenson, 2000) have not found such a correlation.

A major review article on the environmental risk factors for bipolar disorder (Tsuchiya 2003) looked at seven different studies, and found that three of them reported an association between birth complications and risk for bipolar disorder. The article concluded that current evidence was "suggestive but inconclusive" for this particular risk factor.

Studies that examined the possible link between birth complications and bipolar disorder did not necessarily control for genetic risk (that is, the likelihood that the individual had inherited lots of genetic susceptibility). Moreover, some studies that found a positive association included subjects with unipolar depression and schizoaffective disorder, not just bipolar disorder.

There is a stronger association between birth complications and increased risk for schizophrenia, and some have suggested that for babies who have inherited genetic susceptibility to schizophrenia, oxygen deprivation and/or reduced blood flow during birth (caused by obstetric complications) might impair normal brain development. It is possible that something similar may happen for individuals who are genetically susceptible to bipolar disorder; however, the evidence from scientific studies has not shown as strong an association. In fact, one author (Walker et al, 2002) arguing for overlapping genes that contribute to both schizophrenia and bipolar disorder suggested that:

"one or more susceptible genes are shared between schizophrenia and bipolar illness, and can be thought of as predisposing individuals to psychosis...Other genes and environmental factors are likely to have more specific effects and contribute to producing the patterns that psychiatrists recognize as 'classical' schizophrenia and mania. In particular, genes involved in early cortical development and early neurodevelopmental insults causing developmental impairment may put individuals on a trajectory towards schizophrenia rather than bipolar illness."

In other words, Walker et al. proposes that those who inherit the genes predisposing them to general psychosis, and who also experience early environmental insults that impair development, will be more likely to develop schizophrenia rather than bipolar disorder with psychotic features.

Scientific Studies:

• Risk factors in relation to an emergence of bipolar disorder: a systematic review. Bipolar Disord. 2003 Aug;5(4):231-42. Review.
• Schizophrenia and bipolar disorder: similarities in pathogenic mechanisms but differences in neurodevelopment. Int Clin Psychopharmacol. 2002 Aug;17 Suppl 3:S11-9. Review.
• No association between urbanicity of place of birth, season of birth, sibship characteristics, or prenatal exposure to influenza and the risk of bipolar illness in Denmark. Acta Neuropsychiatr. 2000; 12:165. [no online abstract available]
• Pre- and perinatal complications and risk for bipolar disorder: a retrospective study. J Affect Disord. 1998 Sep;50(2-3):117-24
• Obstetrical complications in patients with bipolar disorder and their siblings. Psychiatry Res. 1993 Jul;48(1):47-5

Helpful Actions:

To reduce their children's risk, mothers may want to make extra efforts to avoid any possible delivery complications. The best way to do this is to get early and regular pre-natal care, and to be in the best possible hospital environment in case complications do occur.

One recent study suggested that drinking pomegranate juice during pregnancy can help reduce fetal stress from low oxygen and decreased blood flow, both of which can result from obstetric complications. Another recent study preliminarily suggested that nitrous oxide treatment to low-weight babies can help increase oxygen circulation, which can reduce the potential for brain cell damage after birth.