Novel H1N1 Influenza Virus Impacts Pregnant Women More Severely, Study Says

Pregnant women infected with 2009 novel H1N1 had a higher rate of hospitalization and greater risk of death than the general population due to the H1N1 flu, according to a study in the Aug. 8 issue of the British medical journal Lancet.

The data collected and analyzed by the Centers for Disease Control and Prevention (CDC) are the most comprehensive available to date on the impact of this novel H1N1 flu virus among pregnant women.

"The death of a pregnant woman is always heartbreaking, and unfortunately we have been hearing reports of otherwise healthy women dying from H1N1. If a pregnant woman feels like she may have influenza, she needs to call her healthcare provider right away," said CDC’s Dr. Denise Jamieson, lead author of the study. “Clinicians who treat pregnant women should have a system in place for triaging pregnant women with influenza-like symptoms and they should not delay in initiating appropriate antiviral therapy. Some clinicians hesitate treating pregnant women with antiviral medications because of concerns for the developing fetus, but this is the wrong approach. It is critical that pregnant women, in particular, be treated promptly. "

Six deaths of pregnant women with H1N1 were reported to CDC between April 15 and June 16, 2009, representing 13 percent of the total 45 deaths reported to CDC during that time period.  All were healthy prior to infection of H1N1 and subsequently developed primary viral pneumonia leading to acute respiratory distress requiring mechanical ventilation.  All pregnant women who died did not receive antivirals soon enough to benefit their treatment. The CDC recommends that pregnant women with suspected or confirmed influenza infection receive prompt treatment with antiviral medication.

Based on past influenza pandemics and on seasonal influenza epidemics, pregnant women have increased rates of illness and death from influenza infection.

Despite recommendations from the Advisory Committee on Immunization Practices and the American College of Obstetricians and Gynecologists for inactivated flu vaccine for all pregnant women, seasonal flu vaccine coverage among pregnant women is very low (less than 14 percent).

The CDC has posted clinical guidance for treatment and prophylaxis of pregnant women with suspected or confirmed pandemic H1N1 2009 influenza at http://www.cdc.gov.h1n1flu/clinician_pregnant.htm.