The more the better. That’s the basic conclusion from some researchers in the United Kingdom when it comes to in vitro fertilization (IVF).

Their study confirmed earlier research that certain women can extend their chances of getting pregnant through their ninth IVF cycle.

The study’s findings were published online today in the Journal of the American Medical Association.

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Birth Rates by Cycle

The researchers looked at information from a group of 156,947 women who underwent IVF in that country between 2003 and 2010.

They found that the live birth rate was highest for the first cycle, with 29 percent of women giving birth after one IVF attempt. This rate stayed above 20 percent up to the fourth cycle and then dropped to 15 percent by the ninth cycle.

Sixty-five percent of women achieved a live birth by the sixth cycle, the researchers reported, although a more conservative estimate of the cumulative rate put it at 46 percent at the sixth cycle.

“This study is showing that, from a cumulative standpoint, you can continue to get success as time goes on, in some patients,” Dr. Bradley Van Voorhis, president of the Society for Assisted Reproductive Technology, told Healthline.

“There are some patients,” added Van Voorhis, “where [additional cycles] become fairly hopeless, largely based on age.”

More than 68 percent of women under 40 years of age achieved a live birth by the sixth cycle. This fell to 31 percent for women between 40 and 42 years old, and 10 percent for women over 42.

Researchers defined an IVF cycle as all transfers of embryos — fresh or frozen — resulting from a single treatment of ovarian stimulation.

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More IVF Cycles Is Not Always Best Choice

There is no recommended maximum number of IVF cycles, although the authors and other researchers indicate that some fertility clinics may stop at three or four cycles.

Earlier research, though, supports more IVF cycles. A 2012 study published in the New England Journal of Medicine and done in the United States showed that the cumulative chance of a live-birth increased with additional cycles.

“To me this study is not surprising,” said Van Voorhis. “I think we all recognize that if patients can keep going, and try more and more cycles, that ultimately the cumulative pregnancy rate is going to be quite high.”

However, many patients pay for IVF treatments out of their own pocket, an expense that runs around $12,000. Medications can cost another $3,000 to $5,000.

And each additional cycle can bring with it more emotional stress. So what is clinically possible with IVF may not line up with what’s best for a couple.

“Looking purely at [IVF] outcomes, you could argue that we should keep going because there’s still a good chance for pregnancy,” said Van Voorhis. “Yet from the patient perspective, the emotional toll and the cost become prohibitive to continue.”

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