A team of surgeons completed four womb transplants on American women at Baylor University Medical Center in Dallas last month.
The transplants mark the first living-donor uterus transplants in the United States, Baylor University Medical Center at Dallas said in a statement.
The surgeries were completed between Sept. 14 and 22, though only one of the transplants was successful. According to the hospital, three of the patients were not receiving adequate blood flow to the transplanted organs, so the wombs were removed.
The patients are recovering and should return to normal activity, according to the hospital.
The fourth patient has shown no signs of organ rejection and her tests appear to show good blood flow to the uterus.
“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,” the hospital said in a statement.
In March, the first uterus transplant in the U.S. failed after the patient experienced a “sudden” complication, Cleveland Clinic announced.
The surgery, which took place on Feb. 24, 2015, in Cleveland, initially seemed to be a success.
While the 2015 uterus transplant marked a first in the U.S., there have been successful uterus transplants in Sweden.
A woman in Sweden born without a uterus received one in 2013 from a 61-year-old post-menopausal woman, according to research published in the journal The Lancet.
She later gave birth, offering the first “proof-of-concept for uterus transplantation as a treatment for uterine factor infertility,” according to the report.
The surgeons worked alongside a surgical team from Sweden who have reported five births from transplants they have performed.
Baylor University Medical Center did not release further details on the patients, but said it remains steadfast in its commitment to finding a solution for uterine-factor infertility.