The world's first over-the-counter home fertility test for men has been developed by scientists at Birmingham University.
Millions of men have a low sperm count
The Fertell test works in less than an hour and gives couples an early warning of potential fertility problems.
Researchers looked at samples from 150 men and they claim the test provided an accurate result in 95% of cases.
They said the test, which is available now, could cut the wait for fertility treatment by up to a year.
Mimics the cervix
Professor Chris Barratt, who led the research, said: "At the moment many couples are advised to wait for around a year before seeking medical attention.
"But age can have a very significant negative impact on fertility, so having reliable information at an early stage can be a huge advantage."
To conduct the test the man produces a sample, sets the device and within an hour will find out whether he has enough sperm to fertilise a female egg.
The test works by forcing sperm to swim through a barrier mimicking the female cervix. It then measures the number of sperm which get beyond this point.
If a high enough level of active sperm is present in the sample, a red line indicates a positive test.
During the development of the test the research team analysed more than 3,000 individual sperm samples.
Nationally as many as one in six couples will have to undergo personal testing to assess the possibility of them starting a family.
Research suggests more than two million men may have low fertility and that it may be becoming more of a problem.
Dr Allan Pacey, Senior Lecturer at the University of Sheffield and secretary of the British Fertility Society, said: "This is a neat device which actually examines how well sperm perform under 'test conditions' rather than just simply counting them and seeing how well they move.
"In that way, its a arguably more sophisticated than the standard semen analysis performed in many hospital laboratories."
"The fact that men can take this test at home should help them to overcome their initial embarrassment of going to a hospital and having to produce a sample for analysis there
"It can be a big deal for some men to have their fertility tested and men often fail to keep their hospital appointments for semen analysis which wastes time and resources."
Clare Brown, of Infertility Network UK, said that with many couples delaying a family until later in life, it was important to provide as much information about their current fertility as possible.
She said: "This test can provide them with that information and allow them to identify some fertility problems at an early stage.
"However, it is important that couples are also made aware that other factors can affect their chances of conceiving such as blocked fallopian tubes.
"We would recommend to couples that if they have any concerns about their fertility they speak to the GP for further investigations."