Study Says Pregnant Women Should Get Flu Shot

Carol Pearson
August 09, 2012

The Centers for Disease Control and Prevention is watching a strain of flu that contains a gene from the 2009 H1N1 pandemic flu virus. That 2009 virus infected millions of people around the world. Pregnant women were especially vulnerable and were urged to be vaccinated. But is the vaccination safe for unborn babies? A new Danish study is looking into that question.

During the 2009 H1N1 influenza pandemic, pregnant women faced a greater risk of life-threatening complications and many were hospitalized.

Dr. Michael Katz from the March of Dimes says influenza is a serious disease for both a pregnant woman and her unborn child. "Influenza disease in a pregnant woman is very dangerous for the fetus. It can cause [spontaneous] abortions. It can cause birth defects and prematurity," he said.

That's why U.S. health officials made pregnant women a priority group for getting the H1N1 vaccine during the pandemic. And the US Centers for Disease Control advise women to get the influenza vaccine early in their pregnancy.

During the pandemic, European doctors recommended the same thing. That's not normally the case in Europe, but Dr. Bjorn Pasternak says the pandemic changed things. "During the 2009 H1N1 pandemic we had a special situation; this was actually the first time that pregnant women were recommended vaccination against influenza in many European countries," he said.

Dr. Pasternak led a study of the H1N1 vaccine for the Staten Serums Institute in Denmark. "There was basically no safety data in pregnancy with this specific vaccine prior to its being used in clinical practice," he explained.

The study compared 330 babies whose mothers received the vaccine in the first trimester of pregnancy with the same number of babies whose mothers were not vaccinated.

During the first trimester, a fetus is especially vulnerable to substances a mother might take in.

The researchers found that babies exposed to the vaccine had slightly more birth defects compared to those not exposed. They also found that slightly more babies exposed to the vaccine were born preterm.

But the researchers said the difference -- between the babies who were and were not exposed to the vaccine -- was statistically insignificant, meaning if they compared another group of babies, the results might turn out to be just the opposite.

"We found no increased risk of any birth defect, of pre-term birth or of fetal growth restriction associated with H1N1 vaccination in pregnancy," Dr. Pasternak added.

Dr. Katz agrees. "If the danger of an epidemic were there, in my view, the vaccine should be taken right away," he stated.

The study was published in the Journal of the American Medical Association.