A procedure thought to boost chance of a successful pregnancy for women undergoing IVF has been dealt a blow by research that reveals it does not improve the chances of having a live birth.

An endometrial scratch involves grazing the tissue lining the womb, as occurs when taking a tissue biopsy, in a process that takes about a minute and is similar to a smear test – but more painful and invasive.

Several studies have previously suggested it might offer a benefit in IVF, among them a 2016 study found that while many expensive IVF “add ons” had a dearth of evidence behind them, the endometrial scratch did at least appear to improve the rate of live births. It has been suggested the inflammation triggered by the scratch might help embryos to implant.

Many private fertility centres, including those in the UK, currently offer the procedure with costs reaching as high as £350, although it is not routinely offered on the NHS.

But the new research, the most comprehensive study to date, found that the scratch makes no difference to the chances of women undergoing IVF having a live birth.

“Lots of the studies that have been done so far, they are not the best quality – they are all associated with different risks of bias,” said Dr Sarah Lensen of the University of Auckland who is presenting the findings at the annual meeting of the European Society of Human Reproduction and Embryology in Barcelona. “We wanted to conduct a trial that was really robust and recruited lots of women so we could answer the question [of whether it has a benefit] once and for all”.