The study examined the relationship between obstetric complications, genetic risk and age of illness onset in
bipolar disorder. Thirty DSM-IV bipolar I patients in remission (ages 21-39yr, mean 30.7 + 6.1yr.) and twenty seven healthy controls (ages
19-39yr, mean 27.7 + 7.0yr.) were investigated using structured interview, life chart and pregnancy and birth complications
questionnaire. Family history, pregnancy and birth complications and age of illness onset were collected. Comparisons
were made between patients and controls and also between patient groups with age of illness onset before and after
the age of 21 years.
Obstetric complications were more common in patients (effect size= 0.48) than controls but this was not significant statistically
(Fisher’s exact test, p=0.13). There was a non-significant excess in early onset patients. Family histories of mood
disorder were found in 22 out of 30 bipolar subjects, but rates in early and late onset groups did not differ (p=0.35).
The study failed to find evidence of either increased rates of obstetric complications in bipolar disorder patients or of a
link between age of illness onset and a family history of mood disorders. The power of the study was limited by a sample
size and difficulties in obtaining unequivocal obstetric data. The finding is in agreement with a recent metanalysis. The
large effect size indicates that larger study of obstetric complications in bipolar disorder subjects is justified, looking particularly
for subgroups for which there may be an association between complications and clinical variables.