During pregnancy, women have an increased immune response to influenza, which may explain why infected pregnant women have increased rates of morbidity and mortality, the results of a recent study suggest.
The study, published online on September 22, 2014, in the Proceedings of the National Academy of Sciences, examined natural killer (NK)-and T-cell responses to influenza during pregnancy. Immune responses were measured for pregnant women and nonpregnant controls immediately before and 7 days after they received an inactivated influenza vaccination, and 6 weeks after the women gave birth.
The results indicated that pregnant women had a significantly increased percentage of NK cells producing a response to the pH1N1 virus than nonpregnant women both before and after vaccination. Pregnant women also had significantly increased T-cell responses to the pH1N1 and the H3N2 strains.
The results of the study were surprising because previous research has shown that the overall production of both NK and T cells is suppressed during pregnancy.
“Robust cellular immune responses to influenza during pregnancy could drive pulmonary inflammation, explaining increased morbidity and mortality,” the study authors explained.