In marketing materials for ella, the emergency contraception pill that will be available to American women of child-bearing age under the new health reform plan, a cartoon character egg peeks out from behind a glass door while a cartoon character sperm stands on the steps, apparently cajoling her to come outside.

"I can't come out for five days," the egg tells the sperm.

The ad goes on to tout the drug's "power to help keep these two apart" and says ella, known generically as ulipristal acetate, "provides extra time for extra pregnancy prevention."

But that's not all it does.

"Ella may also work by preventing attachment to the uterus," say materials distributed by Watson Pharma Inc., which sells ella.

It is that effect of preventing the fertilized egg from attaching to the uterine wall that can make ella an abortifacient and has led the U.S. Catholic bishops to criticize the U.S. government's decision to include it among the preventive services for women that nearly every health plan in the U.S. will be required to cover.