Four women became the first in the U.S. to receive uterus transplants from living donors at Baylor University Medical Center in Dallas, according to TIME. 

All the organ recipients were born with a condition called Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome. MRKH is a genetic condition in which the female is born without a uterus. It occurs in about 1 in 4,000-5,000 women in the U.S., according to the National Organization for Rare Disorders. 

Baylor surgeons performed the surgeries, alongside a Swedish surgical team, who are widely considered the world’s experts in uterine transplant. Five births have resulted from transplants they have performed, according to a news release. The surgeries took place between Sept. 14-22. 

Since the first surgery, three patients’ transplanted organs were not receiving viable blood flow and the uteri were removed, according to the release. Those patients are now doing well.

The fourth patient’s follow-up is showing good blood flow and no signs of organ rejection. 

Dr. Giuliano Testa, the lead surgeon and surgical chief of abdominal transplantation at Baylor, acknowledges that these results so far, while disappointing, still show tremendous progress, according to TIME. 

“If you look at this from the science [perspective], it’s something we’ve learned a lot from, and we have a patient who is doing well,” he said.

“This is the beginning of hopefully a great history for medicine,” Testa told TIME. “I am not ashamed of being the one who will be remembered as the guy who did four [transplants] in the beginning and three failed. I am going to make this work. I believe from an ethical and clinical and research point of view, we have our heart in the right place.”

There have been at least 16 previous uterus transplants worldwide, including one in Cleveland from a deceased donor that had to be removed because of complications, according to CBS News. 

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