The team said that the effect of having five cups of coffee a day was very similar to smoking and it could reduce the live-birth rate following IVF by 40 percent.
“Although we were not surprised that coffee consumption appears to affect pregnancy rates in IVF, we were surprised at the magnitude of the effect,” Dr. Ulrik Schioler Kesmodel, of the Fertility Clinicat Aarhus University Hospital in Denmark, said.
However, the researchers say that though their research shows a relationship between coffee and fertility treatments it does not prove a cause-and effect relationship. Therefore they can’t positively say that because a woman drinks too much coffee her IVF treatment will not be a success at all times.
For their study the team followed 4000 women who were undergoing IVF treatment or intracytoplasmic sperm injection treatment for infertility. The information about the amount of coffee they drank each day was collected at the beginning of the treatment and also at the start of every new treatment.
They also considered other factors that could affect a woman’s chances of pregnancy like age, body mass index, smoking and drinking habits. They found that the chances of getting pregnant after the treatments reduced to half for women who drank five or more cups of coffee in a day. Additionally for those who drank less than five cups of coffee, no significant effect was noted on their chances of getting pregnant.
“There is limited evidence about coffee in the literature, so we would not wish to worry IVF patients unnecessarily,” Kesmodel said. “But it does seem reasonable, based on our results and the evidence we have about coffee consumption during pregnancy, that women should not drink more than five cups of coffee a day when having IVF.”
The study’s findings were expected to be presented Tuesday at the annual meeting of the European Society of Human Reproduction and Embryology in Istanbul, Turkey.