However, the procedure presented a serious decision for Chaney. While she already has two daughters of her own, she now faces the possibility of an earlier menopause.
"She won't notice any difference at all in terms of her hormone production or her fertility, except for the fact that, we are predicating, that she will go through menopause two or three years earlier than she would have otherwise," Silber said.
But Chaney says she did not hesitate at the chance to allow her sister to have a natural pregnancy.
"She's my sister," Chaney said. "I think anyone in that same circumstance would do the same thing; just not many people are put into that circumstance. I get to be the lucky one to have all these great experiences."
Silber says that he hopes the technique will someday lead to female cancer patients being able to freeze their ovaries before they undergo therapy, allowing them to preserve their fertility after treatment.
But will the procedure become widely available to most infertile women? Not likely, said Dr. Richard Paulson, director of the USC Fertility in Los Angeles.
He said that for most women, the immunosuppressant drugs necessary to prevent rejection could also severely limit their ability to maintain and complete pregnancy.
"Those medicines are typically quite toxic to the developing fetus, and they would also be toxic to the reproductive tract," he said.
Paulson added that a far simpler method currently exists.
"In most circumstances, it is far easier to transfer one egg than the whole ovary," he said. "It would still be safer to stimulate the sister's ovaries, get a few eggs out, and transfer them to the recipient. This is far and away a simpler way to go."
He says, however, that such operations could be plausible for a wider range of women in the future if researchers perfected the techniques used to freeze whole organs for later use.
And however unusual, the procedure may prove to be a precious gift for Lagos and her husband, Rodrigo. Chaney's rare gift is a true blessing.
"The best thing I can do is be the best parent I can be, the best husband I can be and take care of her sister forever and ever -- love her, be her friend, have her be a part of our lives to really also enjoy what she has given to our family," Rodrigo Lagos said.
"I don't think there's a way to say thank you," Joy Lagos said. "I will thank her by being the best mom that I can. The kind of mom that she is."
To visit Silber's Web site, please click here.
To visit Joy and Rodrigo's blog, please click here.