The first baby to be created from an egg that was matured in the laboratory, frozen, thawed and then fertilised has been born in Canada, scientists report.

The experimental fertility treatment also resulted in three other pregnancies, they added. The research was presented at the annual meeting of the European Society of Human Reproduction and Embryology in Lyon, France on July 2.


An ovary contains many follicles, egg-containing structures that grow and develop between puberty, maturation, and menopause. When a woman is fertile, each month a follicle travels to the surface of the ovary, bursts, and releases an egg in preparation for fertilization. The image above shows follicles which along with their eggs are in various stages of development. Primordial follicles are the form that is present at birth and throughout childhood. The ovaries also contain small numbers of corpus lutea, or burst follicles, which produce the pregnancy hormone progesterone. (Image courtesy US Nat'l Institutes of Health)

The healthy baby girl was born to a patient with polycystic ovarian syndrome, a condition that can disrupt a woman’s menstrual cycle, ability to have children, hormones and circulation, the researchers said.

Twenty patients diagnosed with the syndrome or related conditions took part in a trial at McGill Reproductive Center in Montreal.

Freezing a woman’s eggs, or oocytes, has become an “integral part of fertility treatment,” said the center’s Hananel Holzer, who led the team. New freezing techniques have boosted egg survival and pregnancy rates, he added.

But pregnancies reported to date have resulted from fertilisation of frozen, then thawed eggs collected after women’s ovaries had been stimulated to produce eggs. And this can’t be done in some patients.

In these cases, scientists can collect immature eggs and mature them in the laboratory before freezing them, Holzer said. But before now it wasn’t known whether such eggs could survive thawing and lead to successful pregnancies.

“We have demonstrated for the first time that it is possible to do this and, so far, we have achieved four successful pregnancies, one of which has resulted in a live birth,” he said. The results are preliminary, he added, “and the pregnancy rate is probably associated with a learning curve—three of the pregnancies were achieved in the last five patients.”

The team selected patients with an average age of 30, and who were also infertile. The method still isn’t shown to work in cancer patients, Holzer added.

But in a related study, to be announced at the same conference on July 3, another team of scientists say they’ve made progress toward preserving fertility in childhood cancer survivors—obtaining and freezing eggs from girls as young as five years.

Ariel Revel of Hadassah University Hospital in Jerusalem, a member of the team, said the growing number of survivors of childhood cancers means such techniques would become increasingly important. Childhood cancers tend to have relatively good cure rates, of 70 to 90 percent. But the aggressive chemotherapy usually leads to sterility.

In adult women, ovaries can be stimulated to produce eggs that are removed, fertilised and frozen. In young girls this isn’t possible. Doctors instead typically freeze egg-producing tissue of the ovaries for transplantation at a later date. But freezing often damages the tissue, called ovarian cortex.

As an alternative, Revel and colleague collected and froze individual eggs from the tissue, which are more cold-resistant, they said. To their surprise, the team found eggs in girls between five and 10 years old who had not reached puberty, and were able to extract these with a needle. “No eggs have yet been thawed”, said Dr.Revel, “so we do not know whether pregnancies will result. But we are encouraged by our results so far.”

ABOUT THE AUTHOR

Science writer Jack Lucentini is founder and editor of the World Science science news webzine. He has worked as a staff writer at three daily newspapers, and as a freelance science writer for a range of publications including The Washington Post, Discover magazine and The Scientist magazine. He earned his bachelor's degree at Oberlin College in Oberlin, Ohio in 1993.