Editor’s note: Ruth Faden is the director of the Berman Institute of Bioethics at Johns Hopkins; Anne Drapkin Lyerly is an obstetrician-gynecologist at Duke University Hospital; and Maggie Little is a senior research scholar at the Kennedy Institute of Ethics at Georgetown. This article was distributed by Duke News Service.

DURHAM, N.C. – When diseases like swine flu hit, pregnant women are especially at risk. And yet we know surprisingly little about how to treat them. In its guidelines for the antiviral drugs Tamiflu and Relenza, the Centers for Disease Control and Prevention says that pregnant women infected or at high risk for infection should take the recommended adult dosage: “Pregnancy should not be considered a contraindication” to taking the drugs, because the benefits of treatment “likely outweigh the theoretical risks of antiviral use.”

But we don’t know whether this is true. Concerns about the ethics of performing drug studies on pregnant women mean we know far less about how to treat them. It is perfectly possible that the standard adult dose of antivirals will not work in the pregnant body.

Pregnancy acts as a wild card when it comes to medication. Changes in blood flow, digestion, kidney function and enzymatic activity alter the ways that drugs act on the body. There is almost no data on how antivirals function during pregnancy, and the same is true for many other drugs on the market.

The consequences are potentially profound. One of the antibiotics used for treating exposure to anthrax is metabolized so quickly by the pregnant body that no dose, no matter how large, is likely to be effective. If the threat of widespread anthrax attacks after 9/11 had been realized, pregnant women and their babies would have faced disastrous consequences. We should not make the same mistake in planning for the possible reemergence of swine flu in the fall.

One pregnant woman in America has already died from the flu. Although other health problems complicated her illness, her death is a reminder that we need to understand how to medicate mothers-to-be. Research should be done now, while pregnant women are already taking antivirals.

Studying blood samples from as few as two dozen women would get us a long way toward determining whether the standard dose is effective.