Improving IVF success rates

It could be easier for women to get pregnant through in vitro fertilisation (IVF) in the foreseeable future, thanks to efforts from scientists to eliminate guesswork at critical stages in the process.

The new discoveries are the result of a fruitful research partnership between reproductive biologists Professor Ken McNatty and Dr Janet Pitman, from the School of Biological Sciences, and Professor John Hutton and Dr Jozsef Ekart of Fertility Associates, who have combined their collective expertise on fertility, cell biology and gene mapping to great effect.

Current IVF treatment involves using hormones to stimulate egg production, collecting and fertilising a number of those eggs, and incubating them until the blastocyst stage (an early embryo).

Within three to five days one embryo is chosen to be implanted in a woman’s uterus, and, at that point, most couples are given a 50 percent chance that their treatment will lead to a successful pregnancy.

Part of the problem with the process as it stands, says Ken, is that while embryologists select what they believe is the best candidate to implant, the results are “hit and miss”.

Jozsef says his doctoral research could change that in as little as five years by allowing embryologists to reliably identify the best eggs and embryos.

Using a gene measuring technique pioneered by Janet, Jozsef measured the levels of eight genes the research team suspected might play a role in pregnancy from cumulus cells, which surround and nourish an egg in an ovarian follicle. He then compared the presence of those eight genes with each egg as it developed firstly into an embryo, and subsequently a successful, or unsuccessful, pregnancy.

Jozsef identified three genes that correlated to the successful development of embryos and one to a successful pregnancy.

His results suggest that if a simple test can be developed to check for the presence of these genes, only the best egg need be fertilised.

“These results give us a 75 percent success rate using four genes as markers. But what we really want is 90 percent from a single, high-quality oocyte [egg].”

To that end the research team is applying for funding to reanalyse the cells already studied to identify either more ‘indicator’ genes, or the reverse—genes whose presence indicate likely failure.

Jozsef says understanding more about the genetic variety of eggs and the ovarian follicle within which they develop could provide another breakthrough in IVF treatment.

“Our study also found that follicles develop in a hierarchical way. It’s almost like it’s predesigned which follicle will produce good quality eggs and will ovulate, and which ones are predisposed to dying.”

During IVF an average of nine eggs are collected from a patient and, using a range of treatments, they are incubated and prepared to be fertilised at the same time.

“But despite all of our efforts to synchronise their development, they will never be completely identical. We can’t overrule their pattern of development,” says Jozsef.

“That’s very key, because in the future, we could very easily just select eggs from the single follicle we know produces the best ones.”

Jozsef says it’s only a matter of time before these findings become a reality for couples undergoing IVF.

“Once we have the right tools we’ll be able to measure even more gene expression, even more precisely. It’s refining the method, I think, that will soon lead to being able to tell with certainty which eggs are good and which eggs are not.”