Diet drinks may reduce a woman's chance of getting pregnant during IVF, a study suggests.

Would-be mothers who opted for pop with artificial sweeteners, or put sugar substitutes in hot drinks, produced poorer eggs and embryos, researchers said.

While it is widely believed taking artificial sweeteners is healthier than taking sugar, both options raised the risk of an embryo being found to have at least one deformity.

The findings were based on a study of women undergoing fertility treatment at an IVF clinic and presented at the congress of the American Society of Reproductive Medicine, in Salt Lake City.

Would-be mothers who opted for pop with artificial sweeteners, or put sugar substitutes in hot drinks, produced poorer eggs and embryos, researchers said.

The 524 women were asked about their dietary habits, and whether they who drank diet drinks and coffee with either sugar or artificial sweeteners.

Over two years, the researchers looked at 5,548 egg cells taken from the women undergoing fertility treatment.

They noted whether any form of shape defect was present or absent in the egg.

They also then looked at how the egg did after it was impregnated with sperm to form an embryo on days 2 and 3 after conception.

They found drinkers of both diet and sugared drinks were more likely to produce eggs with defects.

The same women's embryos were also likely to have defects, and were less likely to successfully implant in the womb.

In conclusion, the authors, led by Gabriela Halpern of the Fertility Medical Group based in Brazil write: 'The general population believes that artificial sweeteners are healthier than regular sugar, and is not aware of the dangers hidden behind the promise of reduced calorie food and beverages.

'Patients should be advised about the adverse effect of sugar and mainly artificial sweeteners on the success of assisted reproduction.'

Professor Adam Balen, Chair of the British Fertility Society, said: 'This is a very interesting study that suggests that the 'false promise' of artificial sweeteners that are found in soft drinks and added to drinks, such as coffee, may have a significant effect on the quality and fertility potential of a woman's eggs and this may further impact on the chance of conception.

'These findings are highly significant and relevant to our population. There should be more scrutiny of food additives and better information available to the public and, in particular, those wishing to conceive.

The study of IVF patients found drinkers of both diet and sugared drinks were more likely to produce eggs with defects

'The environment in which the egg develops is very sensitive to external influences and we shouldn't underestimate the potential effects of food additives to reproductive health.

'Couples (both women and men) wishing to conceive should be aware of the importance of healthy nutrition.'

But Professor Richard Sharpe, Group Leader of Male Reproductive Health Research Team, University of Edinburgh, said that it may be that the women who were taking drinks with sweeteners may be obese, and trying to control their weight and he 'would be very dubious about the claims.'

Catherine Collins, registered dietitian and spokesperson for the British Dietetic Association, said that while there may be a 'possible correlation', no causation can be drawn from the limited dietary data provided.

She said: 'Obese women are recommended to lose weight to increase fertility.

'Artificial sweeteners are used by the health conscious to manage calorie intake and by the overweight attempting to lose weight.

'No evidence is presented in this abstract to qualify obesity as a confounding factor influencing oocyte quality, nor whether women had issues with PCOS which is linked to increased body weight and known to influence oocyte quality.

'Failure to address this major confounding factor is a massive oversight.

'Secondly an 'increased frequency' of soft drink consumption is noted- but not the amount consumed.

'If there were a relationship between artificial sweeteners of any type and oocyte quality then it would be expected to be dose related.

'Given the data presented defines neither the portion size nor the frequency of soft drinks it cannot provide meaningful data as to the amount of sweetener consumed by these women sufficient to influence fertility.'

She continued: 'Bottom line? If you're keen to get pregnant then cutting out sugar from your drinks is a positive contribution to reducing calorie intake and managing blood sugar.