Treating pregnant women with novel influenza A (H1N1)

September 1, 2009

Treat pregnant women presenting with influenza-like illness with influenza antiviral medications ASAP.

Treat pregnant women presenting with influenza-like illness with influenza antiviral medications as soon as possible, without waiting for results of testing for influenza-if testing is performed-according to new interim guidelines issued by the Centers for Disease Control and Prevention (CDC).

The guidelines explain that pregnant women are likely to present as others with typical acute respiratory influenza-like illness, including such symptoms as cough, sore throat, rhinorrhea, and fever. Symptoms may also include body aches, headache, fatigue, vomiting, and diarrhea. While most pregnant women will proceed to have a typical uncomplicated course of the flu, illness can progress rapidly for a few, possibly becoming complicated by a secondary bacterial infection, such as pneumonia, and/or causing fetal distress. Adverse pregnancy outcomes and maternal deaths have been reported.

The currently circulating H1N1 flu is sensitive to the neuraminidase inhibitor antiviral medications zanamivir (Relenza) and oseltamivir (Tamiflu). Because the former results in lower systemic absorption than the latter, the latter is the drug of choice in pregnancy. H1N1 is resistant to the adamantine antiviral medications, amantadine (Symmetrel) and rimantadine (Flumadine).

Consider post-exposure antiviral chemoprophylaxis with zanamivir (because of its limited systemic absorption) for pregnant women exposed to persons with suspected or laboratory-confirmed H1N1 virus infection because maternal hyperthermia during the first trimester doubles the risk of neural tube defects and may be associated with other birth defects and adverse outcomes. Similarly, maternal fever during labor is associated with numerous adverse neonatal and developmental outcomes.

For more information, see http://www.cdc.gov/h1n1flu/clinician_pregnant.htm and http://www.cdc.gov/h1n1flu/guidance/obstetric.htm.