Mothers who catch the flu during pregnancy may be almost four times more likely to have a child who develops bipolar disorder, according to a new study published in JAMA Psychiatry.
Bipolar disorder causes unusual shifts in mood, energy, activity levels and the ability to carry out basic tasks. Although some people have their first symptoms during childhood, the disorder often develops in the late teens or early adult years.
“We don’t fully understand this,” said study co-author Alan Brown, M.D. “The best guess is it’s an inflammatory response. It could also be a result of fever.”
Brown, a professor of clinical psychiatry and clinical epidemiology at the Columbia University College of Physicians and Surgeons in New York City, said, “Mothers should stay away from people who have the flu.”
Brown added that “women should not be greatly concerned, because a fourfold increase is pretty high from an epidemiological standpoint, but still the vast majority of the offspring did not get bipolar disorder.”
Brown further explained that “the risk of bipolar disorder in the population is about 1 percent, so if it’s increased fourfold that would make it a 4 percent risk.”
Furthermore, the study only looked at one risk factor for bipolar disorder, not all risk factors, which could skew these results, he noted.
For the study, researchers at Columbia University and Kaiser Permanente identified cases of bipolar disorder by database linkages of a Northern California health plan and a county health care system, along with data from a mailed survey.
The study participants were mothers who gave birth between 1959 and 1966 and their offspring. Researchers found 92 cases of bipolar disorder and compared them with 722 people matched in terms of occurrence of maternal influenza during pregnancy.
Although the research found a link between pregnant women getting the flu and a higher risk of bipolar disorder in their offspring, it didn’t establish a cause-and-effect relationship.
“There is no understanding of the causal factors of this,” said Alan Manevitz, M.D., a clinical psychiatrist at Lenox Hill Hospital in New York City. He was not involved with the study. “Pregnancy itself puts extra stress on women in general,” he pointed out. “Pregnancy also affects the immune system and increases the risk of getting the flu.”
Flu during pregnancy increases the risk of miscarriage, premature birth and low birth-weight infants, Manevitz said.
Source: JAMA Psychiatry