A woman who became infertile in her teens has given birth to a baby girl after receiving ovarian tissue from her identical twin sister, doctors said Tuesday.

U.S. doctors reported the ovarian tissue transplant on the New England Journal of Medicine's website, in what is said to be the first transplant operation of its kind between two different women.

In a five-hour operation in April of last year, doctors removed one ovary from the donor twin, separated tissue that contains the egg-producing follicles, and then grafted a third of the tissue onto each of her sister's undeveloped ovaries.

The donor recipient, Stephanie Yarber, had not had a menstrual cycle since age 14.

By contrast, her sister Melanie Morgan's ovaries worked normally and she conceived three children.

Within three months of the transplant, the donor's menstrual cycle had resumed.

During her second cycle, Yarber became pregnant, naturally.

And on Monday night, Yarber give birth to an almost-eight pound baby girl, said
Roger Gosden, a fertility expert at Cornell University who was part of the research team.

"I had faith it would happen, but after years of praying and wanting kids, we're delighted," she said on learning of her pregnancy, The Times Online reported.

The surgery, which doctors said would likely remain rare, came after two unsuccessful attempts at test tube fertilization using eggs donated by her twin sister.

According to researchers, the transplant is promising news for women who may be infertile.

"The demonstration that ovarian function can be restored and that natural conception and successful pregnancy can be achieved after transplantation of ovarian tissue may have broader implications for preserving fertility in young women, such as those who require potentially sterilizing treatment for cancer," researchers say in the report.