Pregnant women with the H1N1 swine flu are at higher risk of severe illness and death, according to a new US study in the journal Lancet. Pregnant women have always faced a higher risk due to influenza, but the H1N1 virus is hitting them especially hard. “We do see a fourfold increase in hospitalization rates among ill pregnant women compared to the general population,” Dr. Denise Jamieson of the U.S. Centers for Disease Control and Prevention told Reuters. “We’re also seeing a relatively large proportion of deaths among pregnant women.” The study looked at the deaths of six pregnant women (all of whom were healthy prior to infection) out of 45 H1N1-related deaths, reported to CBC from April 15 to June 16. Women should not delay pregnancy due to fears about H1N1, CDC officials said, as there’s no evidence they’re more likely to catch the flu—only that, once they’re infected, they’re at increased risk of severe illness.