The first birth to result from a new technique, whereby immature eggs are matured in the laboratory and then frozen and stored for later use, was announced by Canadian researchers at the annual meeting of the European Society of Human Reproduction and Embryology in Lyon last week.
The technique was trialled on twenty women with polycystic ovarian syndrome (PCOS), a condition which causes fertility problems due to cysts on the ovaries, and which makes women prone to having a severe reaction, known as ovarian hyperstimulation syndrome, in response to conventional fertility drugs.
It is also hoped that the technique could help young girls with cancer, who are often rendered infertile as a result of chemotherapy. However, the research is still in its early stages and this has not yet been tried, warned Hananel Holzer, a physician at the McGill Reproductive Centre in Montreal and Assistant Professor in the Department of Obstetrics and Gynaecology at McGill University, who led the research.
'Until now, it was not known whether oocytes collected from unstimulated ovaries, matured in vitro and then vitrified, could survived thawing, be fertilized successfully and result in a viable pregnancy after embryo transfer', Holzer announced at the meeting.
Holzer reported that in addition to the birth of the first child, who is now one year old and developing normally, a further three women from the trial are pregnant, giving a 20 per cent overall success rate.
If proven successful there are several different groups of women who stand to benefit from this technique, including: prepubescent girls affected by cancer, for which the only current option is to surgically remove and freeze a chunk of the ovary for re-implantation at a later date, running the risk of cancer cells being transferred along with the tissue; and women with hormone sensitive cancers, such as some breast cancers - who like those with PCOS, are unsuitable for conventional fertility treatment due to a high risk of ovarian hyperstimulation syndrome.
Given that only 50 per cent of the 295 eggs collected in the trial survived the freezing and thawing process to be successfully fertilized, Dr Lawrence Shaw, a spokesman for the British Fertility Society, cautioned that 'these pregnancies are an exciting step. However, the pregnancy rate is very low and therefore large numbers of eggs would be needed'.