Swine flu in pregnancy can cause life-threatening disease and warrants treatment with antiviral drugs as soon as possible, a study in the medical journal Lancet found.

The study, to be published in the Aug. 8 issue, found about one in eight people who died after contracting the new virus was pregnant. The hospitalization rate for pregnant women was more than four times that of the general population, the study showed.

The findings support advice from health authorities including the World Health Organization that pregnancy may put women at greater risk of developing complications from the pandemic H1N1 flu. The data collected and analyzed by the U.S. Centers for Disease Control and Prevention are the most comprehensive available to date on the impact of this novel flu virus among pregnant women, the Atlanta-based agency said in a statement today.

“If a pregnant woman feels like she may have influenza, she needs to call her health-care provider right away,” Denise Jamieson, lead author of the study, said in the statement. “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.”

Six deaths of pregnant women with H1N1 were reported to the CDC between April 15 and June 16, representing 13 percent of the 45 fatalities made known to the agency during that period.