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Novel Influenza A (H1N1) Infections Reported in Pregnant Women

The CDC recommends that pregnant women with confirmed, probable, or suspected novel influenza A (H1N1) infection receive antiviral therapy with oseltamivir (Tamiflu).

Pregnancy raises risk for complications related to seasonal as well as pandemic influenza infections such as those caused by the novel influenza A (H1N1) virus. The CDC has recently summarized information about novel H1N1 infection during pregnancy and has issued preliminary treatment recommendations.

Twenty cases of novel H1N1 (15 confirmed and 5 probable) in pregnant women have been reported in the U.S. as of May 10, 2009. Three women were hospitalized, and one of them died. Based on available data, the CDC recommends that pregnant women with confirmed, probable, or suspected novel H1N1 infection receive antiviral therapy with oseltamivir (Tamiflu; preferred for its systemic absorption) for 5 days. Therapy should be initiated as soon as possible, even if >48 hours have elapsed since symptom onset. Acetaminophen should also be administered, as fevers are associated with adverse maternal and fetal outcomes. Pregnant women who have had close contact with someone who has confirmed, probable, or suspected novel H1N1 infection should receive prophylaxis with either oseltamivir or zanamivir (Relenza) for 10 days.

Comment: Both the Advisory Committee on Immunization Practices and the American College of Obstetricians and Gynecologists recommend annual influenza vaccination for all pregnant women. However, because the 2008–2009 seasonal vaccine does not protect against novel H1N1, even vaccinated pregnant women with flu-like symptoms should be evaluated and treated. Although the safety and efficacy of oseltamivir during pregnancy have not been firmly established, the benefits of this antiviral drug are likely to outweigh the risks. Novel H1N1 seems to be resistant to amantadine and rimantadine, so these drugs should not be used in people with suspected novel H1N1 infection.

— Anna Wald, MD, MPH

Published in Journal Watch Women's Health May 18, 2009

Citation(s):

Centers for Disease Control and Prevention (CDC). Novel influenza A (H1N1) virus infections in three pregnant women — United States, April–May 2009. MMWR Morb Mortal Wkly Rep 2009 May 15; 58:497.

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