Flu in Pregnancy Linked to Fourfold Risk of Bipolar Disorder

A study links flu in pregnancy to a fourfold increased risk of having a child that would develop bipolar disorder in adulthood. The study, published in the journal JAMA Psychiatry, adds to the growing evidence of shared underlying causes and illness processes with schizophrenia, which in some studies has also been linked with prenatal exposure to influenza.

"Prospective mothers should take common sense preventive measures, such as getting flu shots prior to and in the early stages of pregnancy and avoiding contact with people who are symptomatic," Alan Brown, M.D., M.P.H, of Columbia University and New York State Psychiatric Institute, said in a press statement. "In spite of public health recommendations, only a relatively small fraction of such women get immunized. The weight of evidence now suggests that benefits of the vaccine likely outweigh any possible risk to the mother or newborn."

This study is the first of its kind that provides clues on maternal influenza or bipolar disorder connection. With the help of physician-based diagnoses and structured standardized psychiatric measures, researchers followed families in the same HMO. They worked on data from Kaiser-Permanente, county and Child Health and Development Study. The database allowed them to include several cases with maternal flu exposure information.

The researchers followed 92 children among a third of children born in northern California county during 1959-1966. These kids developed bipolar disease, and researchers compared the rates of maternal flu diagnosis during pregnancy and matched it with a control group of 722.

They noticed a fourfold increased risk associated with influenza infection during pregnancy. However, if the flu occurred in the second or third trimester, the risk was higher. Also, flu exposure was linked to a sixfold increase in a subtype of bipolar disorder with psychotic features.