The first mammal birthed its first warm, blood-smeared offspring about 160 million years ago, setting a biological precedent that has largely remained unchanged. Only female members of a species, born with wombs, can carry and deliver babies. But doctors have recently made stunning advances in their ability to transplant uteruses into people who don’t have them, and on Friday, a woman who received one of those transplants became the first mother to give birth to a healthy baby in the United States.

The unprecedented, victorious birth took place at Baylor University Medical Center in Dallas in November. Only eight other babies have been born to women who have received uterine transplants, and all of those births occurred in Sweden’s Sahlgrenska University Hospital, where doctors pioneered the research to help women born without a uterus or whose uteruses were damaged by illnesses such as cancer.

It goes without saying that transplanting a uterus is no easy feat, making this achievement especially exciting for American scientists.

“This first live birth to a uterus transplant recipient in the United States was a milestone in our work to solve absolute uterine factor infertility; but, more importantly, a beautiful moment of love and hope for a mother who had been told she would never be able to carry her own child,” said Dr. Giuliano Tesla, the principal investigator of the Baylor University trial.

leonardo da vinci uterus sketch
The uterus is a living organ that protects and nourishes a fetus as it develops.

The process, which involves transplantation of a living organ and its associated immune-rejection risks, is by no means perfect. According to the New York Times, four of the eight transplants in the Baylor study failed and had to be removed, and two of the women are still trying to conceive. One other woman in the trial, however, is currently pregnant.

Once doctors work out all the kinks in the uterine transplant process, it will have the potential to help an estimated 50,000 women in the U.S. who cannot conceive. The women in the study have a condition called Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome, which caused them to be born without a uterus.

This research also opens up the possibility that people other than females will someday be able to give birth. In an interview with Inverse in 2015, Dr. Christine McGinn, a transgender medicine specialist, said that male motherhood is not just possible but likely.

“It’s a little bit less complicated to transplant a uterus into a biological female — it’s like swapping out an engine,” she said. But transplantation into males is possible because, anatomically speaking, males and females aren’t really that different. “What’s great about a uterus is that it’s completely regulated by hormones. A lot of its function is hormone-driven, not nerve-driven.”

The main obstacle to seeing this procedure become mainstream for both women and men is, of course, money. The Baylor University research, estimated to cost hundreds of thousands of dollars, is covered by research funding, but there’s no guarantee that insurance companies — which, for the most part, don’t even cover infertility treatments — will foot the bill.