Caffeine consumption could influence women's fertility treatment after research has found that it can affect the fallopian tubes.
According to a team from the University of Nevada School of Medicine, muscle activity in the fallopian tubes is hindered by a high caffeine intake.
The researchers experimented with mice, but Professor Sean Ward, who worked on the report, said that the findings go some way to explaining why a high caffeine intake reduces a human female's likelihood of becoming pregnant.
He explained that the actions of specialised pacemaker cells in the walls of the fallopian tubes are hindered by caffeine.
The eggs are then unable to move down the tubes when women consume too much caffeine because they are reliant on the coordination of the tube's contractions.
Professor Ward added: "As well as potentially helping women who are finding it difficult to get pregnant, a better understanding of the way fallopian tubes work will help doctors treat pelvic inflammation and sexually-transmitted disease more successfully."