A team of doctors from the Baylor University Medical Center in Dallas performed four breakthrough uterus transplants between Sept. 14 and Sept. 22 on four women who had Mayer-Rokitansky-Küster-Hauser (MRKH) syndrome and were born without wombs. 

According to Time, three of the uterus transplants were removed after tests found that the organs were not receiving normal blood flow. One recipient still has the transplanted uterus and is showing no signs of rejection so far.

"[The patient's] tests are showing good blood flow to the uterus. There are also no signs of rejection or infection at this time," the Baylor University Medical Center announced in a press release. "We are cautiously optimistic that she could ultimately become the first uterine transplant recipient in the U.S. to make it to the milestone of uterine functionality."

Uterus transplants from live donors had been successfully performed at Sweden's University of Gothenburg, where five out of nine transplant recipients have given birth to healthy babies. The first baby to be born from a transplanted womb came out in 2014 from a 36-year-old woman who was a recipient from a post-menopausal donor friend.

Two members of the surgical team from the University of Gothenburg worked alongside the Baylor team in performing surgeries on the four patients in Dallas last month. The Swedish team has also been reviewing the three unsuccessful transplants to determine what went wrong.

The surgery in Dallas is the second time a womb transplant was attempted in the U.S. The first one happened in February in the Cleveland Clinic involving uterus from a deceased donor. However, two weeks following the transplant, the recipient Lindsey McFarland acquired an infection, causing the transplant to be removed. According to a report from Time, uterus transplants are estimated to cost around $150,000 to over $500,000 and are typically non-insurable as they are still experimental.

According to Baylor, a woman with a successful uterus transplant could attempt in vitro fertilization (IVF) in six to 12 months if she wants to get pregnant. IVF is required because their ovaries are not connected to their transplanted wombs, and after having at least two children, the uterus will be removed.