Women who use complementary therapies while trying to conceive by IVF are less likely to get pregnant than those who use conventional medicine alone, research indicates.

A study of 818 Danish fertility patients revealed that pregnancy rates were about 20 per cent lower among users of alternative medicine, such as reflexology and acupuncture, than among those who did not use such treatments.

The findings could mean that complementary medicines that have a biological effect, such as herbal remedies or nutritional supplements, interfere with fertility drugs or other aspects of IVF treatment.

Women who turn to alternative medicine, however, tend to be more stressed by their infertility, and may have been trying for longer to get pregnant. The lower success rate could reflect that these patients are willing to try anything to improve their chances of having a child.

“It may be that complementary therapies diminish the effectiveness of medical interventions,” said Jacky Boivin, of Cardiff University, who led the research. “Or it may simply be that persistent treatment failure encourages women to seek out complementary and alternative therapies.”

Edzard Ernst, professor of complementary medicine at Exeter University, said: “Similar associations have been made in cancer patients. Those who use complementary or alternative medicine [CAM] are on average more distressed and more depressed. The important question is whether the chicken or the egg came first.

“The most likely explanation is that those women who are prone to stress and have more health problems are more likely to try CAM. So CAM could only be a marker, and not the cause of stress and lower success rates.”

The study, which was conducted with the University of Copenhagen, found that 31 per cent of the fertility patients had used an alternative treatment, with reflexology and nutritional supplements the most popular.

Such patients suffered from greater stress, and the researchers said that they could have turned to complementary medicine to address this. Previous small studies have indicated that techniques such as acupuncture may help with relaxation.

Dr Boivin said: “We found that women who went on to use complementary therapies, for example reflexology and nutritional supplements, during their treatments were more distressed and emotionally affected by their fertility problems than nonusers.

“This difference in stress may mean that women used complementary and alternative therapies for stress reduction, and if this were the case it would be important for future research to establish whether these achieve this goal more effectively than conventional psychological therapies.”

The team now intends to follow up the patients over five years to assess pregnancy rates over a longer period. “It is important to do this because we are concerned that, with persistent treatment failure, women might become more and more susceptible to deceptive advertising about ineffective complementary and alternative therapies or other unproven treatments,” Dr Boivin said.