Children whose mothers were diagnosed with the common flu during pregnancy had as much as a four times greater risk of developing bipolar disorder later in life than children born to mothers who did not have the flu during pregnancy, according to a study of 214 people born between 1955 and 1966 in Alameda County, California. Of the children born during this time, 92 were identified as having bipolar disorder later in life.

nearly 4-fold increase in the risk of bipolar disorder

The mothers of all of these children were part of the Kaiser Permanente Medical Care Plan, and they were all recruited for the study back during the 1955-1966 period by the Child Health and Development Study (CHDS), a health collaboration between Kaiser Permanente and several universities, funded by the US National Institutes of Health. The children were compared to 722 other control subjects, and researchers found a "significant, nearly 4-fold increase in the risk of BD [bipolar disorder]" as they reported in a study published in the journal JAMA Psychiatry last week. However, the authors note that the results need to be independently reproduced among other people in order to fully verify the increased risk.

Nonetheless, one of the authors of the study, Alan Brown of Columbia University, said the results should be seen as evidence that pregnant mothers should take care to avoid getting the flu. “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," Brown said in a statement published on the National Institutes of Health website. The US Centers for Disease Control and Prevention says that the flu shot is safe for pregnant women.