THURSDAY, Nov. 30, 2016 (HealthDay News) -- Some fertility clinics in the United Kingdom offer little evidence to back up claims about treatments other than standard in vitro fertilization (IVF), according to a new study.

Researchers examined the websites of 74 British fertility clinics. They identified 276 claims of benefit at 60 centers related to more than three dozen fertility treatments. These treatments ranged from screening blood tests to costly egg-freezing packages.

Of those claims, only 29 percent offered statistics to support the claims of improved fertility outcomes, the study found.

Only 13 websites included any references, and there were only 16 published references. Of those, only five were of high quality, according to the study published online in the journal BMJ Open.

"Our findings demonstrate that whilst many claims were made on the benefits of fertility treatments, there was a lack of supporting evidence cited, with the majority of the websites providing no sources for claims made," study lead author Carl Heneghan and colleagues wrote. Heneghan is director of Oxford University's Centre for Evidence Based Medicine.

"There is a need for more information on interventions to be made available by fertility centers, to support well-informed treatment decisions," the study authors said in a journal news release.

In a related study published in the BMJ, Heneghan and his colleagues searched for evidence to support 38 treatments offered by British fertility centers on top of standard IVF. They found that most of those were not supported by good evidence.

The researchers said there is "an urgent need for randomized controlled trials for many interventions that are currently being offered." They added that "changes in guidance" are needed to help couples make informed decisions.

More information

The U.S. National Institute of Child Health and Human Development has more on infertility treatments.