Many pregnant women fail to get immunized against influenza. This puts their child at risk for bipolar disorder, schizophrenia and autism.
Pregnant mothers' exposure to the flu was associated with a nearly fourfold increased risk that their child would develop bipolar disorder in adulthood, in a study funded by the National Institutes of Health. The findings add to mounting evidence of possible shared underlying causes and illness processes with schizophrenia, which some studies have also linked to 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,"... The weight of evidence now suggests that benefits of the vaccine likely outweigh any possible risk to the mother or newborn."
The nearly fourfold increased risk implicated influenza infection at any time during pregnancy, but there was evidence suggesting slightly higher risk if the flu occurred during the second or third trimesters. Moreover, the researchers linked flu exposure to a nearly sixfold increase in a subtype of bipolar disorder with psychotic features.
A previous study, by Brown and colleagues, in a related northern California sample, found a threefold increased risk for schizophrenia associated with maternal influenza during the first half of pregnancy. Autism has similarly been linked to first trimester maternal viral infections and to possibly related increases in inflammatory molecules. [emphasis mine]