Penn Medicine on Thursday announced that it had performed two successful uterus transplants, and had formed a national scientific consortium with two other pioneers of the experimental procedure.

Researchers from the University of Pennsylvania, Baylor University Medical Center in Dallas, and the Cleveland Clinic gathered in Washington on Thursday to brief congressional staff on the state of uterus transplantation. The hearing also featured Baylor uterus transplant recipient Jennifer Dingle, her husband, and their baby.

“We don’t have any specific requests in terms of legislation,” Kate O’Neill, an obstetrician-gynecologist who co-leads Penn’s program, said by phone. “We just wanted to educate and talk about the barriers that exist" for women seeking such a transplant.

Baylor researchers have estimated at least 500,000 U.S. women of childbearing age are infertile because of a missing or non-functioning uterus.

Baylor, which launched its clinical trial of uterus transplantation in 2016, has had three births as a result. The Cleveland Clinic delivered its first baby from such a transplant in July.

Penn has not released any information about its two transplant recipients, or whether they have gotten pregnant or given birth. Penn’s clinical trial began in 2017.

» READ MORE: Pa. woman donates her uterus to help a stranger experience motherhood

Only about 50 uterus transplants have been done worldwide, most with organs from living donors. In May, Heather Bankos, a nurse and mother of three from Macungie, near Allentown, traveled to Baylor to donate her uterus to a recipient.

» READ MORE: 'Social egg freezing' raises new questions about when it's too old to have a baby

Uterus transplantation remains controversial. It involves major surgery, costs about $200,000 that is not covered by insurance, and is not life-saving, like a vital organ transplant. When the transplant is successful — and it may not be — the recipient must take anti-rejection drugs until giving birth; then the recipient may elect to have the uterus removed.