Fighting flu while pregnant
Pregnant women get sicker from the flu than other healthy adults. Now researchers think they know why.
Expectant moms have an unusually strong immune response to influenza, a study published in Proceedings of the National Academy of Sciences found. This was a surprise; most immune responses are weakened by pregnancy to protect the fetus from rejection by mom’s body.
The study was the first to examine how immune cells taken from pregnant women react to influenza viruses, including the H1N1 strain that caused the 2009 flu pandemic. H1N1 made pregnant women’s natural killer and T cells produce excess cytokines and chemokines. These molecules attract other immune cells to the site of an infection, which could be increasing the women’s pneumonia risk.
“Too many immune cells are a bad thing in the lung, where you need air space,” says Catherine Blish, MD, PhD, assistant professor of infectious diseases and the study’s senior author.
“We now understand that severe influenza in pregnancy is a hyperinflammatory disease rather than a state of immunodeficiency,” she adds. That means anti-inflammatory therapies may be added to the treatment arsenal.