(CNN) For the first time, a baby has been born to a woman who received a uterus transplant from a deceased donor, according to Hospital das Clínicas at the University of São Paulo School of Medicine in Brazil.

The uterus or womb, which is shaped like a topsy-turvy pear and sits within the pelvis, is a female reproductive organ that houses and nourishes the fetus until birth . At least a dozen children in Sweden, the United States and Serbia have been born to women with transplanted uteri donated by a living relative, noted the authors of the study , which was published Tuesday in the medical journal The Lancet.

"The results provide proof-of-concept for a new treatment option for absolute uterine factor infertility," wrote co-authors Dr. Dani Ejzenberg, an ob/gyn at the University of Sao Paulo and Hospital das Clínicas in Brazil, and Dr. Wellington Andraus, a transplant surgeon at the Sao Paulo University School of Medicine in the study. Less than 5% of women worldwide have some type of "absolute uterine factor infertility," in which an abnormality of the womb interferes with fetal development.

The Brazilian team followed protocols established by Dr. Mats Brännström and his team at the University of Gothenburg in Sweden, where the first successful uterus transplant, that one from a living donor, was performed in 2013. That recipient mother gave birth in 2014.

From transplant to birth

for published case studies.) Her diagnosis: The transplant recipient, who had been born without a uterus, was 32 years old at the time of the surgery in September 2016. (The patient's identity remains anonymous, which is typicalfor published case studies.)Her diagnosis: Mayer-Rokitansky-Küster-Hauser syndrome , a genetic condition that affects one in 4,500 women and causes a patient's vagina and uterus to be either absent or underdeveloped, although her external genitals appear normal and her ovaries still function and contain eggs.

Months before receiving a uterus transplant, the patient underwent in-vitro fertilization. This resulted in eight good-quality early-stage embryos, which were cryopreserved in the hopes of being used after a uterus transplant.

The donor, a 45-year-old woman who died of a stroke, was deemed a good candidate because she had had three vaginal deliveries during her life, she had no reported sexual disease and her blood type, O-positive, matched that of the recipient.

The procedure to transfer the uterus from donor to recipient lasted more than 10 hours. The surgery involved connecting the recipient's veins and arteries, ligaments and vaginal canals with the donated uterus. For eight days, the recipient remained in the hospital, where she received five immunosuppression drugs, which control the body's natural instinct to fight off and reject a transplanted organ.

Five months after the transplant, the recipient showed no signs of rejecting the uterus, and for the first time in her life, she experienced menstruation. Ultrasound scans also showed no abnormalities.

After seven months of cautious watching and waiting, doctors implanted a single fertilized egg, though in previous uterus transplants, doctors waited a full year to implant. The shorter timetable was intended to reduce patient expenses and risk, because the possibility of the body rejecting an organ can increase over time.

Pregnancy was confirmed 10 days later. Throughout the pregnancy, all the usual tests showed a normal fetus with no anomalies. Other than a kidney infection treated with antibiotics at 32 weeks, the mother had no issues during her pregnancy and continued her immunosuppression regimen to prevent rejection of the implanted womb.

A girl weighing nearly 6 pounds was born on December 15, 2017, at 35 weeks and three days -- a late pre-term birth. Ejzenberg and Andraus said Brännström's group "recommended delivery between 34 and 36 weeks due to the risk of restriction of fetal growth due to immunosuppressive therapy."

A sonogram shows the baby developing normally within the transplanted uterus.

The mother delivered via c-section, which included a removal of the transplanted uterus so she could stop using immunosupressive drugs, according to Ejzenberg and Andraus. The organ showed no evidence of rejection, only the usual changes that occur during pregnancy. Both mother and child were discharged from the hospital three days later.

At the age of 7 months and 20 days when the case study was written, the baby continued to breastfeed and weighed nearly 16 pounds.

The baby will celebrate her first birthday within two weeks, Ejzenberg and Andraus said. Mother and child have experienced no complications or abnormalities.

This birth is the first uterus transplant of any kind performed in Latin America and the first using a cadaver organ. Previous attempts at using a cadaver uterus have not resulted in a live birth.

Ejzenberg and Andraus said their team's success "brings hope to other centers that believe in this type of transplant and that have not been successful until [this] moment. It is also a source of hope for patients who do not have a family member or close friend to donate the uterus."

Why this is unique

Dr. Andrew Shennan, a professor of obstetrics at Kings College London, told the Science Media Centre that what is unique about this case is that the pregnancy occurred "in spite of the uterus (womb) being without oxygen for 8 hours before transplant." In fact, the new study proves that it could remain functional after cold, oxygen-less storage at least four times as long as the average time after live donation: nearly eight hours, versus less than than two.

Shennan, who was not involved in either the transplant or the birth, added that this case "opens the possibility of women donating their womb following death, as with many other organs." And "rather than relying on live donors, a surrogate or adoption," women who are infertile due to uterine factor infertility might soon have another option.

have occurred in Europe (Sweden, Czech Republic, Germany, and Serbia), they have also been done in Asia, the Middle East and North America. He added that 53 of the transplants involved women born with no uterus. Brännström wrote in an email that "56 uterine transplant procedures have been performed worldwide," and although halfhave occurred in Europe (Sweden, Czech Republic, Germany, and Serbia), they have also been done in Asia, the Middle East and North America. He added that 53 of the transplants involved women born with no uterus.

These transplants have yielded "13 babies born worldwide" via uterus transplants, including the birth documented in the new case study, Brännström said. His own team conducted a series of transplants in multiple women resulting in several live births.

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Though the success of uterus transplants has been proven, Brännström said, "it is important that it also works with a deceased donor, with longer ischemic time and less time to investigate the organ." Ischemic time is the amount of time a donated organ remains chilled and without blood flow. The technique still needs to be "replicated by several teams around the globe" for further validation, he said.

The American Society for Reproductive Medicine recognizes uterus transplantation as a "successful medical treatment of absolute uterus factor infertility" yet cautions that the procedure is still "highly experimental" in nature. At the time they wrote the study, the authors recorded 10 cadaver uterus transplants attempted or underway in the United States, Turkey and the Czech Republic.

Brännström, though, feels hopeful and believes that future transplants will not only create new life, they will "greatly increase the quality of life for parents and grandparents."