A Brazilian baby will celebrate her first birthday later this month, less than two years after her mother—unable to carry a pregnancy because she lacked a uterus—underwent a transplant from a deceased donor. The mother is the first in the world to give birth after such a transplant, a feat doctors were not sure would ever be possible.

The baby girl is healthy and developing normally, according to Dani Ejzenberg, the doctor at the University of Sao Paulo in Brazil who led the transplant team.

For years researchers have been trying to help women who had been either born without uteruses or lost them for medical reasons to carry their own children. About a dozen babies have now been born from uteruses provided by living donors—usually the recipient’s mother, sister or friend—out of about 50 attempts worldwide. In 2011 a team in Turkey was the first to transplant a uterus from a deceased donor, but the procedure did not lead to a live birth.

Ejzenberg says that attempt inspired him to begin a program in Brazil. He traveled to Sweden to learn from doctors there who have the most experience with uterine transplantation. He also tried the procedure on a second Brazilian woman, but she had to have the uterus removed two days after the operation because of complications. Two more women in his program are awaiting suitable donors.

In the successful case, published Tuesday in The Lancet, the donor was a 45-year-old mother of three who died from a rare type of stroke, and also donated her heart, liver and kidneys. The unnamed uterus recipient was a 32-year-old woman born without a uterus, but otherwise healthy.

The transplant was performed September 20, 2016, and a fertilized embryo was implanted about seven months later. The baby was born by cesarean section between 34 and 36 weeks at the Hospital das Clinicas, University of Sao Paulo School of Medicine. Ejzenberg says he wanted to deliver the baby a few weeks early to avoid potential problems late in the pregnancy. Several of the Swedish women who had received uteruses from living donors experienced complications from the immunosuppressive medication needed to keep their bodies from rejecting the transplant.

The Brazilian woman did not have any pregnancy problems, Ejzenberg says, but he removed the uterus during the C-section because he wants to focus on helping more women have a single child rather than on one woman having more than one. For future procedures he hopes to cut down on the time to transplant by removing the uterus before other organs, like the heart and kidneys. A research team at Baylor College of Medicine has shown other organs do not suffer if the uterus is removed first, he says, noting that in the successful transplant he had to wait three hours before getting access to the uterus.

These are still early days for uterine transplants, says Kate O’Neill, co-lead investigator for the University of Pennsylvania’s uterus transplant program, who was not part of the work in Brazil. It is not clear yet, for instance, whether transplants from live or deceased donors will end up being more successful in the long run, she says. “That’s why I think it’s important to do both,” she adds.

With a living donor, the surgery can be scheduled when it’s convenient for the surgeons, and there is time to do a thorough assessment of the donated organ to make sure it is suitable, she says. With a deceased donor, things are a little more rushed and the timing might not be ideal, O’Neill notes, but surgeons can take more tissue from the vagina and blood vessel network than is possible with a living donor.

Another unknown is how likely the body is to reject a transplanted uterus, and thus how much antirejection medication the recipient would need, O’Neill says. Each organ type triggers a different level of immune response, she says, and because the uterus is only needed for a short time—rather than a lifetime, as with a kidney or heart—patients may be able to get away with less medication. The drugs have triggered pregnancy complications in some of the Swedish patients, including kidney problems and preeclampsia, she notes.

Three teams in the U.S., including O’Neill’s, are now working on uterine transplants. Baylor has had two successful births from live donations; Cleveland Clinic is working toward deceased donations; and her own program will be performing both living and deceased donor transplants over the next year. Uterine transplantation began in other countries where there are legal or ethical barriers to surrogacy—getting someone else to carry the pregnancy—O’Neill says.

O’Neill says the work on transplantation is important both as an option for infertile couples and to increase scientific understanding of the uterus and pregnancy.