To be candidates for the procedure, women had to be of childbearing age (mostly in their 30s) and not have a uterus. This transplant is designed to be only temporary, though; the idea is that the women will become pregnant, have one or two children, and then have the uterus removed. This is because, after the operation, the women have to take anti-rejection drugs, which suppress the immune system and make them more vulnerable to diseases and infections, according to Mats Brännström, the Swedish team leader. These drugs do cross the placenta in "negligible" quantities and could affect the developing fetus, said Doris Ramirez Nessetti, a gynecologist at the AllCare Medical Center in Venice, Florida. Cyclosporine, one of the most common immunosuppressant drugs, has been shown to negatively impact fetuses in animal trials but no controlled studies have been conducted to see if it works the same in humans, she said.