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Depressed pregnant women respond more strongly to flu viruses

October 28, 2009 |  1:30 pm

PigDepressed pregnant women respond more strongly to the seasonal flu vaccine, producing higher levels of potentially damaging cytokines--a finding that could help explain why pregnant women have about six times the normal risk of hospitalization and complications from pandemic H1N1 influenza.  An immune overreaction to the virus is thought to be responsible for many of the complications of influenza.

Dr. Lisa Christian, a psychiatrist at Ohio State University, and her colleagues reported the finding today in the journal Brain, Behavior and Immunity. The results appear to emphasize the need for pregnant women to be immunized against swine flu. Typically, only about 12% to 13% of pregnant women are immunized against seasonal flu, and it is not clear that vaccination rates will be higher with swine flu, despite the clear risk of not doing so.

Pregnancy suppresses certain functions of the immune system to prevent rejection of the fetus and to protect the fetus from the inflammation that accompanies fevers and other illnesses. Christian and her colleagues had previously reported that depression in pregnant women and those subjected to other stressors can exacerbate the immune changes, leading to higher levels of various potentially damaging immune molecules in their blood stream.

In the new study, 22 pregnant women filled out a questionnaire about their depression symptoms and gave a blood sample before being immunized against seasonal flu. A second blood sample was obtained six to nine days later. The higher the women scored on the standardized test for depression symptoms, the higher the levels of immune molecules in their blood at the second assay. The elevations were mild, but the assumption is that levels would be much higher accompanying an actual flu infection. High levels of such inflammatory molecules have previously been linked to an increase in preterm births and in pre-eclampsia, which is characterized by high blood pressure and the potential death of the fetus and the mother.

Women who were unhappy about their pregnancies had significantly more symptoms of depression than those who were pleased. Women with less social support and more frequent hostile social interactions were also more likely to be depressed.

"Inflammatory responses to vaccination do no harm, are mild, and typically go away within a few days," Christian said. "But an extended inflammatory response to vaccination, such as the one seen in women with the most depressive symptoms, isn't expected, and it serves as a way to estimate how somebody might respond to an actual infection or illness." So get vaccinated.

-- Thomas H. Maugh II