Valencia, Spain  - A 39-year-old Spanish former breast cancer patient will become the world's first woman to give birth to twins after receiving a transplant of her own ovarian tissue, officials said Tuesday in the eastern city of Valencia.

Women who are treated with chemotherapy or radiotherapy often experience precocious ovarian failure, health official Manuel Cervera explained.

The Valencian woman, however, had ovarian tissue extracted before her cancer treatment and retransplanted after it, restoring her hormonal functioning.

The woman underwent in vitro fertilization, and is in her 15th week of pregnancy.

"This pregnancy opens the real possibility for cancer patients to become mothers," Cervera said.

The woman was treated by Doctor Peset Hospital and the Valencian Institute of Infertility.