Younger women undergoing fertility treatment may stand a better chance of getting pregnant with a new procedure that does not stimulate the ovaries with powerful hormone-containing drugs, doctors said yesterday.
Findings from the first fertility centre in Britain to use in-vitro maturation (IVM) as an alternative to IVF reveal that pregnancy rates are comparable between the two techniques but only for women under 35. In IVF, women are given hormones for about two or three weeks to stimulate their ovaries to produce mature eggs before they are surgically removed for in vitro fertilisation. In IVM, however, immature eggs are removed from the ovaries without the use of drugs and matured in the laboratory before being fertilised with sperm.
The new technique, which has only recently been introduced to Britain, is considered to be safer than conventional IVF because it does not increase the risk of potentially lethal hyperstimulation syndrome, where the ovaries respond adversely to the hormones used during IVF treatment.
Tim Child, of the Oxford Fertility Centre, said that 70 women in Britain had undergone IVM in the past year and for the 40 patients who were under 35 the pregnancy rate was 48 per cent – compared to a pregnancy rate of about 55 per cent for women undergoing conventional IVF.
The percentage of under 35-year-olds achieving a clinical pregnancy – where the heartbeat of the baby has been detected – was 33 per cent. Just 10 babies of mothers undergoing IVM and attending the Oxford centre have so far been born, so it is still too early to estimate an accurate live-birth rate, which is 31 per cent for IVF.
"What we've found looking back on the first year of using IVM is that it works particularly well for a group of women at the younger end of the scale that we have treated," said Dr Child.
"It's an improvement in that we've worked out which patients do best with IVM, so it's about offering it to the right couples," he said.
About 900 babies have been born worldwide by the IVM technique. The first IVM babies in Britain were born last year after the Oxford Fertility Centre was given a licence to use the procedure by the Human Fertilisation and Embryology Authority (HFEA).
The HFEA's experts found that there was no evidence to suggest that IVM was dangerous either to women or to their babies – although further safety studies are still in progress.
Dr Child said that when IVM was first used, pregnancy rates and live-birth rates were relatively low compared to conventional IVF but better laboratory procedures, as well as patient selection, had improved the success rate significantly. "I'm not sure we will ever get better than IVF but the aim is to achieve the same success rate. The advantages of IVM are so great – it is safer and easier. Women who have had both say that they prefer IVM because they do not need several weeks of drug treatment," Dr Child said.
Svend Lindenberg, of the Copenhagen Fertility Centre, who pioneered IVM, said it was best suited to younger women who have regular periods.