Caution urged over claim scratching womb boosts chances of successful birth
Scratching the inside of the womb before conceiving a baby may double the chances of a successful birth, research suggests.
But experts urged caution over the study findings and stressed that "endometrial scratch" was not a pleasant procedure.
They said there was insufficient evidence to recommend such a step to ordinary couples wanting to conceive naturally.
International trials are now under way to investigate whether the procedure might be worth considering for women undergoing IVF (in-vitro fertilisation) treatment.
Endometrial scratch involves causing a small injury to the lining of the womb using a catheter tube about the thickness of a straw.
It is basically the same procedure employed to remove biopsy samples from cancer patients.
The idea is that doing this somehow makes the womb "stickier" and more receptive to the embryo, which stands a greater chance of implanting.
A review of eight trials with more than 1,000 women planning to undergo insemination or conceive spontaneously appeared to show that endometrial scratching really does improve the odds of giving birth.
The study was conducted by researchers from the Cochrane collaboration, which assesses medical evidence to inform policy makers.
Based on the trials analysed, it found that endometrial scratch roughly doubled the chance of live birth compared with no intervention.
The procedure increased the normal likelihood of a successful live birth or on-going pregnancy over a set amount of time from around 9% to between 14% and 28%.
However Sarah Lensen, from the University of Auckland, New Zealand, who led the review, pointed out that research evidence was not of a high standard.
She said: "The results must be treated with caution."
The findings were presented at the annual meeting of the European Society of Human Reproduction and Biology (Eshre) taking place in Helsinki, Finland.
British experts said despite its increasing popularity the jury was still out on whether endometrial scratch should be recommended, and in what situations.
Obstetrician Professor Nick Macklon, from the University of Southampton, who is director of the city's Complete Fertility Centre, said: "There's no evidence of good enough quality to imply that couples setting out to conceive spontaneously should seek this treatment from their doctors."
British Fertility Society chairman Adam Balen, Professor of Reproductive Medicine & Surgery at Leeds Teaching Hospitals, said: "We're certainly not suggesting that women who want to conceive should go out and have this procedure."
The experts stressed that scratching the inside of the womb caused a significant degree of discomfort.
In one of the reviewed studies, patients gave the procedure an average pain score of six out of 10.
Scientists are still not sure how endometrial scratch works. One theory is that it stimulates the regeneration of new cells in the womb lining. Another is that it triggers a beneficial form of inflammation.