Flu is more likely to cause severe illness, hospitalization, or death in pregnant women than in women who are not pregnant. Pregnant woman with flu also have a greater chance for serious problems for their fetus, including preterm labor and delivery. Flu shots will protect pregnant women and their fetuses and will even protect the baby after birth. However, despite public health recommendations, only a fraction of pregnant women receive flu shots.
Because flu can create serious problems in pregnancy, scientists wondered if flu during pregnancy may also cause long-term problems for the child. Researchers in the Epidemiology Branch of the Division of Intramural Population Health Research identified a group of women who were covered by the same insurance plan and who were pregnant between 1959 and 1966. They then followed up with the children 40 years later. They found that pregnant mothers’ exposure to the flu was associated with a dramatically increased risk that their child would develop bipolar disorder in adulthood. Moreover, the increased risk was even higher for a subtype of bipolar disorder with psychotic features.
These findings reinforce recommendations that prospective mothers get flu shots prior to and in the early stages of pregnancy and avoid contact with people who have flu symptoms. In addition, the results may add to emerging evidence that bipolar disorder and schizophrenia may share some of the same underlying causes because some studies have also linked schizophrenia to prenatal exposure to influenza (PMID: 23699867).