TORONTO — Montreal researchers have pulled off a Canadian fertility first that may have huge implications for women hoping, for health or personal reasons, to preserve their ability to bear children beyond the time-frame Mother Nature envisaged.

The team, from the McGill Reproductive Centre, has perfected a technique to flash freeze unfertilized eggs. The success rate -- in other words, the number of eggs still viable after they've been frozen and thawed -- is an impressive 95 per cent.

In late April, a Montreal woman gave birth to a boy who was born from an egg that had been frozen for two months and then thawed, fertilized and implanted into her womb. The unidentified infant is believed to be the first successful birth in Canada resulting from frozen eggs.

A leading medical ethicist said the development could dramatically alter the field of reproduction.

"This is like changing the chronology of reproduction. You don't have to do it when nature determines it should be," said Dr. Margaret Somerville, founding director of McGill University's centre for medicine, ethics and the law.

Another six women have also conceived in this manner and are due to give birth in coming weeks, said Dr. Seang Lin Tan, chair of McGill's department of obstetrics and gynecology and director of the McGill Reproductive Centre.

In the first human trial of the procedure, 15 women were stimulated to produce eggs which were harvested, flash frozen, thawed and implanted. The success rate -- about 40 per cent -- is "comparable to using fresh eggs in most IVF (in vitro fertilization) programs," Tan said Monday in an interview from London.