The New England Journal of Medicine (NEJM) published a new study on the experience of pregnant women in our current pandemic…the net-net is that they don’t fare well if they become ill.

Big Pregnant Woman
As in previous influenza epidemics and pandemics, pregnant women with this pandemic strain of H1N1 appear to have an increased risk of severe disease.

From April 23 to August 11, 2009, a total of 10% of the 1088 patients who were hospitalized with or died from 2009 H1N1 influenza, as reported to the California Department of Public Health (CDPH), were pregnant.  A recent report from the first month of the outbreak noted that the rate of hospitalization among pregnant women was approximately four times the rate in the general population. The NEJM report describes the clinical course of the disease and characteristics of hospitalized pregnant, postpartum, and nonpregnant reproductive-age women with 2009 H1N1 influenza for whom data were reported to the CDPH in the first 4 months of the pandemic.  If you are pregnant and debating about getting the vaccine, read this article!


From April 23 through August 11, 2009, the CDPH and 61 local health jurisdictions performed enhanced surveillance of cases of 2009 H1N1 influenza that required hospitalization and those that were fatal. A case patient was defined as a person who was hospitalized for 24 hours or more and had influenza-like symptoms with laboratory results indicative of 2009 H1N1 influenza.

Cases were reported by providers and hospitals to local health jurisdictions. The mechanisms used to capture cases differed among the local health jurisdictions and included active surveillance conducted by hospital infection-control practitioners, case identification through laboratory surveillance, and passive reporting by clinicians. For each case, demographic, clinical, laboratory, and radiographic data, as well as information on the hospital course, were reported on a standardized case-history form and submitted to the CDPH.

A review of all pregnant, postpartum, and nonpregnant case patients of reproductive age (15 to 44 years of age) was performed. Pregnant patients were those who were pregnant at the time of onset of influenza symptoms. Postpartum patients were those with an onset of influenza symptoms during the first 2 weeks after delivery. For pregnant and postpartum patients who were admitted to an intensive care unit (ICU) while ill, an obstetrician–gynecologist from the research team contacted health care providers when possible to obtain additional detailed information about complications during delivery and the course of the maternal illness.

Study Findings

In this large series of pregnant and postpartum patients who were hospitalized with or died from 2009 H1N1 influenza, 95% of the pregnant patients were infected in the second or third trimester, and almost one fifth required intensive care. One third of the pregnant patients had medical conditions besides pregnancy that are recognized risk factors for complications from influenza. Eight patients who were hospitalized had an onset of symptoms within 2 weeks post partum; half required intensive care and two died, highlighting the continued high risk immediately after pregnancy. The pregnant women were less likely to have underlying medical conditions than the nonpregnant women hospitalized with 2009 H1N1 influenza. Although pregnant women frequently presented with mild or moderate symptoms, many had a rapid clinical progression and deterioration.

This study continues to emphasis the risk that pregnant women face if they come down with the flu. As the current pandemic unfolds, pregnant and postpartum women should be counseled about the importance of vaccination.  Women need to exercise caution and obtain the H1N1 vaccine as soon as possible from their obstetrical providers.