Doctors are often compelled to make quick decisions in life threatening cases with only limited information. Unfortunately, pregnant women are now going to be put in the same situation.

The H1N1 flu has taken an extraordinary toll among pregnant women. A new vaccine is now available. Because of the nature of the emergency, there has not been time to do any long term studies of the vaccine. Yet pregnant women will need to make a decision as soon as possible on whether to be vaccinated.

Many illnesses are more severe during pregnancy, but the H1N1 influenza has had an unexpectedly devastating impact among pregnant women. According to the CDC, there have been approximately 700 reported cases of H1N1 in pregnant women since April. Of these, 100 women have required admission to an intensive care unit and 28 have died. In other words, 1 out of every 25 pregnant women who contracted H1N1 died of it. By any standard, that is an appalling death rate.

There seem to be two reasons for the dramatically increased death toll. The first is the altered immune status of pregnant women making them particularly vulnerable to the virus. The second is that pregnancy compromises lung function. If a pregnant woman gets pneumonia as a complication of the flu, it is particularly difficult to insure that she gets enough oxygen.

We should ensure that pregnant women do not get H1N1 influenza and the best way to do that is by vaccination. The new H1N1 vaccine is similar to other influenza vaccines. We know that other influenza vaccines are not harmful in pregnancy, and there is no reason to believe that the H1N1 vaccine will have any side effects that differ from those normally expected after vaccination. There are no adjuvants added to the vaccine, either, so there will be no danger from adjuvants. However, there has been no time to study the long term effects of the vaccine, so no one can be sure about side effects.

Pregnant women are rigorously counseled to avoid any drugs, diagnostic tests, or treatments that might impact the developing embryo or fetus. Most women reflexively fear the idea of vaccination in pregnancy, although vaccination for many diseases presents no problems in pregnancy. The Centers for Disease Control and physicians are very concerned that pregnant women will refuse vaccination, with potentially lethal results.

How should pregnant women decide what to do? The best place to start is with what we know for sure. We have a great deal of evidence that H1N1 influenza is particularly lethal in pregnant women. To put it in perspective, the chance of a pregnant woman dying from H1N1 is greater than the chance of a heart patient dying during triple bypass surgery. That is not a trivial risk.

We have no evidence that the vaccine will cause any harm to pregnant women or their unborn children beyond the side effects associated with other flu vaccines, such as local irritation at the vaccine site, or the rare complication of Gullain Barre Syndrome. We have no reason to expect that the H1N1 vaccine will be any different.

It would be much easier to make the decision if we knew more, if we had some idea of how extensive the fall outbreak will be, if we had longer experience with the specific vaccine. Unfortunately, that information is not available to us and by the time it becomes available may more pregnant women may sicken and die unnecessarily.

Given the dramatic threat and the fact that we know of no unusual complications of vaccination, the decision seems clear. Every pregnant woman should get vaccinated as soon as possible.

Amy Tuteur is an obstetrician-gynecologist who blogs at The Skeptical OB.

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