The first mother-to-daughter egg donation has been announced by doctors.

If the Canadian girl, now aged seven, ever uses the eggs to have a baby, she would effectively be giving birth to her own half-sister or half-brother.

Flavie Boivin, from Montreal, was born with Turner's syndrome (TS), a genetic condition that causes impaired growth and learning difficulties. TS also destroys eggs, leading to an unusually early menopause.

A patient's fertility can be preserved by freezing her ovarian tissue or eggs before the disease progresses. However, this carries a high risk of miscarriage or babies being born with genetic abnormalities.

Another option is egg donation, often by a second-degree relative such as a cousin or aunt. In Flavie's case, her mother stepped in to help her daughter by making a gift of her eggs - the first time this has ever happened.

French Canadian lawyer Melanie Boivin, 35, spoke about her decision, which she made after attending a conference on Turner's.

"The role of a mother is essentially to help her children and if I could do anything in my power to help Flavie I had to do it, and because of my age I had to do it now," she said.

"I told myself if she had needed another organ like a kidney I would volunteer without any hesitation, and it is the same kind of thought process for this.

"I do not want to oblige her to use the eggs, I want to give her the option. The thing I was most sad about her syndrome was her fertility issue. I was trying to open another door for her.''

The eggs were collected and frozen by doctors at the McGill Reproductive Center at the Royal Victoria Hospital in Montreal.

Ms Boivin underwent two cycles of ovarian stimulation and egg collection. A total of 21 mature eggs were frozen in liquid nitrogen.

Dr Seang Lin Tan, who led the team, presented details of the egg donation at the annual meeting of the European Society of Human Reproduction and Embryology in Lyon, France.

He said Ms Boivin had made an "emotional'' appeal to the hospital's ethics committee for the procedure to be allowed.

"It will still be up to her daughter whether she uses these eggs herself when she grows up, or whether she exchanges them for other eggs which come from a stranger,'' said Dr Tan.

He acknowledged it was unclear how long the eggs could be frozen without damage.

"No one knows about how long eggs can be frozen for,'' he said.

"But we do know that children have been born from embryos frozen for more than 10 years so we hope it does not matter how long these eggs are frozen for.''

Flavie's father, Martin Cote, 35, is a financial analyst. The couple also have two other children, Jeremie, 11, and Clara, two. Clara does not have Turner's and boys do not suffer from the condition.

Ms Boivin said her family had been highly supportive. The only negative reaction had come from an ethical professor in Toronto who did not think the interests of the unborn child had been sufficiently taken into account.

"It is very difficult to imagine how I will react when the situation of Flavie using the eggs to have a child arises,'' said Ms Boivin.

"She will need to make the decision and if she wants to go further, I will be supportive and will see this child as any other grandchild.

"Flavie has the perfect name. In French 'vie' means life, and she is full of life. She is always happy and smiling and she is a very social child. She is brilliant at school.

"Turner's syndrome means she is lacking a couple of genes and we don't know which ones exactly are missing but she has problems growing and needs to take growth hormone, she will always be infertile and she has a lot of problems with her ears. She has had several ear operations and has urinary infections.

"Her cognitive abilities are normal and she was very quick to speak and write, but she has problems with spacial skills and difficulties with maths and planning.

"She has some problems with motor skills and walked later than normal, she takes longer to learn those things but gets there in the end.''

Dr Tan said other women may now want to freeze eggs for their sick daughters to use in the future.

"If a mother found out her child had cancer and would need treatment that might make her menopausal at a young age, then the mother might want to freeze her own eggs for her daughter,'' he said.