Doctors at Belgium's Erasme Hospital claimed a world first on Wednesday in extracting and later successfully re-implanting ovarian tissue to enable a young Congolese-Belgian woman to give birth.

Writing in the journal Human Reproduction, gynecologist and fertility specialist Dr. Isabelle Demeestere said it was the first time that medically induced infertility in someone so young had been overcome.

At the age of 11, the girl was ailing with sickle cell anemia. She was given a bone marrow transplant combined with chemotherapy, a practice that stimulates blood production but risks damaging the ovaries.

Doctors removed fragments of her right ovary when she was 13 at the onset of puberty.

Implanted a decade later

A decade later, they grafted the extracted ovarian tissue onto the woman's other ovary. Eggs grew in that inserted tissue and two years later the woman gave birth to a healthy boy - in November last year.

"It was a very happy moment," said Demeestere, who kept the woman's identity anonymous.

In previous cases, older women have had ovarian tissue removed and later transplanted to give birth, but none was treated in childhood, she said.

"We didn't know what would happen when you transplant tissue [back] into a patient that is completely immature," Demeestere said. "But once I saw that she had started ovulating and her hormone profile was normal, I was quite sure she would get pregnant."

Freezing ovarian tissue had been the only option for preserving fertility, she added.

'Hope for girls'

Pediatric oncologist Dr. Jill Ginsberg of the Cancer Center at the Children's Hospital in Philadelphia said the Belgian case gave "hope for girls."

"To have a child go through this and be able to have a baby years later is just remarkable," Ginsberg said. "But his is still going to be a long shot for anyone going through this kind of treatment."

Removing ovarian tissue was "no small undertaking" when children needed chemotherapy, added Professor Adam Balen of Leeds Centre for Reproductive Medicine.

The director of the Assisted Conception Center at Guy's Hospital in London, Dr. Yacoub Khalaf, said the procedure had worked "since youngsters survive chemotherapy much better than adults."

ipj/sms (Reuters, AFP, AP)