Fertility experts have made a discovery that could help doctors to better understand why IVF fails repeatedly in some women.

With IVF (in vitro fertilisation), a woman's eggs are fertilised with sperm outside the body in a test tube and then placed back inside her womb. The first IVF baby was born in the UK in 1978 and since then, more than four million children have been conceived worldwide using this treatment.

Success rates can differ greatly depending on a couple's particular circumstances. Some women have to undergo multiple attempts before a successful pregnancy occurs, while others never become pregnant.

However, experts in the UK and the Netherlands have identified a specific genetic pattern in the womb that may predict whether or not IVF treatment will be successful.

According to the study's co-lead, Prof Nick Macklon of the University of Southampton, these findings could lead to a new test which would help patients to understand how likely they are to become pregnant before they begin fertility treatment.

It could also offer guidance on whether or not they should continue with treatment even if it has been unsuccessful in the past.

"Many women undergo a number of IVF cycles without success despite having good quality embryos and, up to now, it has been unclear whether or not the lining of the womb may be the cause of that.

"We have now shown that an abnormal gene expression in the lining can be identified in many of these women and that a specific gene 'fingerprint', when present, is always associated with failure, which is very significant in aiding our understanding of IVF failure," Prof Macklon explained.

The findings are based on data from 43 women with recurrent implantation failure and 72 women who gave birth after undergoing IVF or another type of fertility treatment known as ICSI (intra-cytoplasmic sperm injection).

An analysis of biopsies taken from the 43 women found that 80% had an abnormal gene profile in their womb's lining, but this profile was not present in the women who had given birth.

"What this tells us is that a large proportion of women who suffer recurrent implantation failure may be infertile due to a problem with the receptivity of their uterus.

"Their chances of achieving successful pregnancy are likely to be very small and this information gives clinicians much more clarity in counselling patients as to the wisdom of investing further time, effort and money in ongoing treatment," commented Prof Frank Holstege of the University Medical Center Utrecht in the Netherlands.

He said at the same time, patients who have not had success with IVF but do not have this genetic pattern ‘could be advised to persist as they have a much better chance of achieving a pregnancy'.

Prof Macken added that while this is a ‘very significant development', the next stage will be to trial it as a clinical test ‘to study its effectiveness on a wider scale'.

Details of these findings are published in the journal, Nature.