As a neonatal intensive care nurse, Heather Bankos has seen the heartbreak that comes when babies are born fighting for life, when they don't make it and when complications mean women who have lost children will never again be able to conceive.

Bankos, 31, a mother of three, has spent nearly a decade giving her medical attention and comfort to families on their most joyous and difficult days, but she wanted to do more.

So she gave her uterus.

In May, Bankos, of Macungie, Pa., donated her uterus to a stranger through a uterus transplant clinical trial at Baylor University Medical Center in Dallas.

Uterus transplant is an experimental procedure that enables a woman who does not have a functioning uterus to become pregnant and give birth. Baylor researchers estimate that absolute uterine factor infertility, meaning the uterus is nonfunctioning or nonexistent, affects from 500,000 to three million U.S. women of childbearing age.

Still in its early days, receiving a uterus transplant involves major surgery, costs about $200,000, and isn't covered by insurance. But researchers are hopeful that uterus transplants can one day become more widely available for women who want to bear a child themselves but were born without a uterus, had to have theirs removed, or whose uterus does not function.

"It's more than donating an organ. It's donating an entire experience of being pregnant and giving birth," said Liza Johannesson, a gynecologic surgeon and medical director of uterus transplant at Baylor.

When Baylor launched its uterus transplant trial in 2016, doctors were overwhelmed with responses from women — women who wanted to donate their uterus.

Within two weeks, at least 200 women had called, asking how to be donors. Now there are hundreds of women from 41 states on the donor list, Johannesson said.

"All of a sudden we have women reaching out to us wanting to give up their uterus," she said. "We didn't know why these women wanted to give up part of themselves."

As researchers worked through the list, vetting potential donors, they got their answer.

"They all say they want to give an experience they had themselves, that it was very important to them to carry their babies. I think that's kind of beautiful," Johannesson said. "It's a perfect organ to give away. Once you're done with it, you really don't need it anymore. It's not a kidney or part of a liver you may need later in life."

For the woman receiving the organ, the transplant is just the beginning.

Transplant recipients require in vitro fertilization to become pregnant, and must take powerful immunosuppressive drugs for as long as they have their donated uterus, so the body does not reject the organ.

In Baylor's clinical trial, women will be able to keep their donated uterus for no more than five years because of the toll immunosuppressive drugs take on the body, which can include a high risk of cancer.

Bankos had been considering becoming a surrogate — in which she would become pregnant and give birth to a child for another person — when she read about Baylor's program and knew she wanted to participate.

Bankos' husband, Brendon, was supportive. Together they put away a little extra money each month. Donors' medical services are covered by the trial, but they must pay for their own travel expenses. "We were in agreement that I was going to help somebody," she said. "I was just waiting to find somebody who needed me."

When she'd been matched with a stranger who needed her, she was nervous but excited, too. "Having that special bond between you and that baby," Bankos said, recalling how overwhelming it was to hold each child after hours of difficult labor. "It's a great feeling and I wish everyone could have it."