Experts have believed for a long time that pregnancy weakens a woman's immune system, making her more susceptible to illnesses like the flu. However, research released just before the start of this flu season indicates that, in the case of the flu, the opposite may be true during pregnancy.
It is a given that, during pregnancy, women have more problems, and are more likely than other demographic groups to die from complications after the flu. In the past, scientists have speculated that this is from a pregnancy-induced suppression of the immune system. It's understood that there is an immune system phenomenon that helps women's bodies not reject their fetuses.
The research from Stanford states that scientists were able to show that women have decreased natural killer cells and T-cell functional responses to both tumor promoters and a particular lipid-soluble molecule produced by the bacterium Streptomyces conglobatus, but found their defenses were not weakened by the flu, according to Science News. Actually, the response was significantly greater. It should be noted that the research did not only measure a woman's response to the flu itself, but also the response women experienced during pregnancy after the flu vaccine, according to the text of the actual Stanford research.
"Intriguingly, these differences were present prior to influenza vaccination and were further enhanced after vaccination. Collectively, our data suggest a model in which an enhanced inflammatory response to influenza during pregnancy results in additional pathology in pregnant women, providing a potential explanation for their disproportionate morbidity and mortality."
The researchers explained their study's method in the Proceedings of the National Academy of Sciences of the United States. Specifically, the researchers analyzed the immune responses of 21 women during pregnancy against the immune responses of 29 women who were not pregnant. They studied the pregnant women just before being vaccinated with an inactivated flu vaccine, seven days after administration of the flu vaccine, and six weeks after giving birth. The results were surprising.
Pregnant women had a significantly increased natural killer cells that produced a response to the flu, compared to women not experiencing pregnancy before the vaccination, and the immune response was even more extreme after vaccination with the flu shot. The researchers concluded that the reason why women might feel so much worse from the flu during pregnancy could be from the overactive immune response to the flu virus.
"Robust cellular immune responses to influenza during pregnancy could drive pulmonary inflammation, explaining increased morbidity and mortality."
"I wonder if this is an inflammatory pathway that is normally activated later in pregnancy to prepare the body for birth, but that flu happens to overlap with the pathway and aberrantly activates it too early," Catherine Blish, lead author on the study, said according to a Stanford report.
Did you experience a more severe reaction to the flu during pregnancy or have you seen it happen in your loved ones?
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