It's time to test the new swine flu vaccine in pregnant women.

Studies of adults and children are going so well that the National Institutes of Health announced Wednesday it is opening the research to 120 women in their second or third trimester of pregnancy.

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The flu always is dangerous to pregnant women, and 6 percent of U.S. swine flu deaths so far have been among pregnant women.

The new swine flu vaccine is just a recipe change from the regular flu vaccine long given to pregnant women and thus shouldn't cause new safety concerns. But the studies are key to learning what dose is required for protection.

Click here for more information on H1N1 from the CDC.

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