July 5, 2012 -- What a woman drinks and eats -- especially coffee and fat -- may affect her chances of success with infertility treatments, two new studies suggest.
"If you drink more than five cups of coffee a day, you reduce your chances of achieving pregnancy during IVF treatment by 50%," says researcher Ulrik Kesmodel, MD, PHD, a consultant gynecologist at the Fertility Clinic of Aarhus University Hospital in Denmark.
Eating high amounts of saturated fats and polyunsaturated fats also made IVF success less likely, says researcher Jorge E. Chavarro, MD, an assistant professor of nutrition and epidemiology at Harvard School of Public Health.
But eating higher amounts of monounsaturated fats increased the chances of having a live birth, he tells WebMD.
Both studies were presented in Istanbul at the 28th annual meeting of the European Society for Human Reproduction and Embryology (ESHRE).
However, other experts consulted by WebMD warn that both studies are small and it's too soon to recommend drastic dietary changes based on the findings.
"In a small study, all sorts of spurious results can come out," says Richard Paulson, MD, professor of reproductive medicine and head of the fertility program at the University of Southern California in Los Angeles.
About 1 in 6 couples worldwide have some type of infertility problem during their reproductive years, according to ESHRE. Since 1978, about 5 million babies worldwide have been born with the help of fertility treatments.
For the coffee study, Kesmodel evaluated nearly 4,000 cycles in women undergoing infertility treatments at a Denmark clinic.
At the start of the treatment and before each treatment cycle, the women reported how much coffee they drank per day. Kesmodel also took into account age, smoking, alcohol habits, weight, and other factors that may affect the success of fertility treatments.
Those who drank more than five cups of coffee a day cut their chances of achieving pregnancy.
"They have only half the chance of achieving pregnancy compared to women who do not drink coffee at all," Kesmodel tells WebMD.
The finding needs to be repeated in other studies, Kesmodel warns. But if the current study turns out to be valid, the effect of heavy coffee drinking on IVF success would be about the same as the known risk of smoking during IVF.
"I am not saying people [undergoing IVF] should not drink coffee at all," Kesmodel tells WebMD. "One or two cups a day would likely be okay."
He can't explain the link, and points out that he found evidence only of an association between heavy coffee drinking and odds of IVF success, not proof that coffee causes IVF failure.
Diet & IVF Success: Fats
In previous research, Chavarro and his team found links between trans fats and saturated fats and fertility problems.