London (PTI): The desire to carry forward their genes is making would-be grandparents pay thousands of pounds for infertility treatment to their children, a recent study in UK shows.

One in eight couples undergoing infertility treatment have their bill subsidised by would-be-grandparents, a survey by a magazine has found.

Londoners are the most likely to borrow with almost one in three having their clinic bills subsidised by their mothers and fathers.

On average, would-be grandparents are paying 5,413 pounds towards the conception of their future grandchildren.

The survey, by Red magazine, found the average cost of fertility treatment to be 6,368 pounds, MailOnline reported.

But the cost could go up to 15,000 pounds per course and some women needed multiple treatments.

"That's a lot of money being spent on infertility treatments, which begs the question, who's paying?", Sam Baker, the magazine's editor-in-chief, said.

"With both parents working, many grandparents are already relied upon for childcare and it seems financial involvement is the next step," he said.

Medical professionals say was not unusual for potential grandparents to wanting to help foot the bill.

"Fertility is not just about having children, it is about having grandchildren. Couples often say 'our parents are desperately keen to become grandparents and want to help us'," said Dr Geeta Nargund, of the Create fertility clinic in central London.

The survey of 2,628 woman also found that one in three had problems starting a family.

It also revealed that seven in ten childless women over the age of 30 worry about their fertility and 'in the back of their minds' think of turning to IVF.

However, just a quarter of women having IVF had a baby - that fell to 13 per cent for the over 40s, the survey found.

Four in ten of the 25 to 35 year-old polled said they would consider freezing their eggs, despite the process offering no guarantee of future motherhood.