Though the overall statistics for swine flu are small (45 reported deaths reported in the US between April 15 and June 16), once infected with swine flu, pregnant women are four times more likely than sick individuals in the general population to be hospitalized.

Both physical and immunological changes occurring in the body during pregnancy play into the increased risk for pregnant women. Structurally, the expanding uterus impedes the expansion of the lungs, potentially increasing the risk of complications such as pneumonia. Biologically, a woman’s immune system is affected by pregnancy. To accommodate the “foreign body” of the developing fetus, the body’s immunological responses are dampened, leaving the body open to more severe illness.

It is as of yet unclear whether pregnant women are more vulnerable to/likely to contract swine flu than the general population, but this study makes clear that, once contracted, swine flu is more likely to develop into a serious illness for pregnant women.