Two women required intensive care unit admission, but there were no fatalities among 98 pregnant women admitted to one hospital for 2009 influenza A (H1N1), according to findings from a Spanish cohort presented here at the 50th Interscience Conference on Antimicrobial Agents and Chemotherapy.

“Pregnancy is classically considered a risk factor for severe influenza disease based on previous research data,” said Jose R. Pano-Pardo, MD, of the University Hospital of La Paz in Spain, who presented the findings. “We wanted to investigate the risk factors for severe disease among a cohort of pregnant women and non-pregnant women of child-bearing age, which we determined was 15 to 45 years.”

The prospective cohort trial was conducted at 13 hospitals in Spain belonging to the REIPI (Spanish Network for Research in Infectious Diseases). Eligible participants included 98 pregnant women and 112 non-pregnant women, all of reproductive age. All participants had a proven diagnosis of the 2009 strain and were admitted to a participating hospital between June 12 and Nov. 10, 2009.

“Diagnosis was based on real-time [polymerase chain reaction] testing,” Pano-Pardo said. “Early antiviral therapy was defined as being administered less than 48 hours after onset of symptoms, and severe disease was defined as ICU admission or death.”

Non-pregnant women were more likely than pregnant women to be admitted to the ICU, 18% vs. 2% (P<.001). There were also more deaths among non-pregnant women, five vs. zero, (P=.06).

Non-pregnant women had more associated comorbid conditions than pregnant women, 44% vs. 18% (P<.001). The most commonly observed condition in both groups was asthma, at a rate of 20% among non-pregnant women and 13% among pregnant women. “We also observed fewer severe symptoms among pregnant women at presentation,” Pano-Pardo said.

The time between onset of symptoms and hospital admission was 3 days among non-pregnant women and 2 days among pregnant women (P<.001). Fewer non-pregnant women received antiviral therapy, 52% vs. 28%, (P=.001).

“Regarding clinical outcomes, the length of hospital stay was shorter in pregnant women,” Pano-Pardo said. “Also, a higher number of non-pregnant women received early antiviral therapy.”

Results of a multivariate analysis and a matched cohort analysis indicated that pregnancy was not associated with complicated influenza. “Chronic pulmonary disease and morbid obesity were risk factors for severe disease, but not pregnancy,” Pano-Pardo said.

“A lower threshold for hospital admission in pregnant women might partially explain the results, since less severely ill patients were considered in the pregnant women subcohort,” Pano-Pardo said in an interview. “Nevertheless, an increased awareness among clinicians regarding pregnant women might have warranted a higher proportion of early antiviral therapy, which is the main modifiable favorable prognostic factor recognized to date.

“In summary, the data presented show a lower risk of severe disease among pregnant women with influenza 2009 A (H1N1) than previously suggested but are in coherence with other studies including consecutive admitted patients,” he said. “These data suggest the need and opportunity to perform a systematic review of outcomes of influenza 2009 A (H1N1) among pregnant women.” – by Rob Volansky

For more information:

• Pano-Pardo J. V-652. Prognosis of 2009 A (H1N1) Influenza in Admitted Pregnant Women in a Context of Early Diagnosis and Therapy. Presented at: 50th Interscience Conference on Antimicrobial Agents and Chemotherapy; Sept. 12-15, 2010; Boston.