Fertility experts today welcomed the development of the world's first over-the-counter home fertility test for men.
The breakthrough technique, claimed to have a 95% accuracy rate, is designed to give couples early warning of potential reproductive problems.
Dr Allan Pacey, secretary of the British Fertility Society, which represents reproductive medicine professionals, said the new Fertell device could encourage men with fertility problems to seek medical help sooner.
The new test indicates with a red line if a high enough concentration of active sperm successfully swim through an "obstacle course" designed to mimic the female cervix.
Dr Pacey said: "If what this device does is to get men to actually consider that there is a possibility there is a problem and get it checked out, and if they don't get a red line gets them to the clinic a bit sooner, that's a good thing.
"The question mark is what the GP would make of a man who does not get a red line. I would hope they would say, this is good enough for getting the guy referred."
Dr Pacey, a senior lecturer at Sheffield University, said the test could also help tackle very high non-attendance rates at male infertility clinics.
He added: "It's actually quite a neat little device.
"In the laboratory you would look at the sample down the microscope, count how many sperm there are and look at how well they swim.
"Not may labs go the extra mile and put the sperm through a test. Because it's a test for the home you only get a yes or no answer, but it's a yes or no answer based on a bit of logic."
He warned that there would be some situations where men could get a positive result but still be infertile - and where they failed to get a red line but were still able to get their partner pregnant.
He said: "It depends on many factors and one failed test isn't necessarily going to doom you to male infertility for the rest of your life."
The new device was developed by Birmingham University researchers in collaboration with London-based reproductive products company Genosis.
It will be on sale nationwide in high street chemist Boots for £79.99 in a kit for couples including male and female fertility tests.
Around one in seven couples in the UK are said to experience problems in conceiving. The problem is equally divided between men and women.
At present couples having difficulty conceiving are often advised to wait for about a year before seeking medical attention.
One in 15 men experience some fertility problem, although about half of couples with difficulties eventually manage conception.
The new male test works by forcing sperm to swim through a barrier which mimics the female cervix.
The device then measures the concentration of active sperm - known as motile sperm - able to swim beyond that point.
If the level is high enough then a red line indicates a positive test.
The kit reproduces the temperature conditions of a woman's body. Sperm are deposited in a container and a column of artificial cervical mucus is heated automatically to 37C.
Professor Chris Barratt, from Birmingham University's medical school, who led the research team, said: "The test has the advantage of being extremely straightforward to use.
"The man produces a sample, sets the device, and within an hour will be able to assess whether he has enough sperm to fertilise the female egg.
"Having a simple home test also takes the pressure off men, who may feel embarrassed at the prospect of providing a sample in a clinic."
Prof Barratt admitted that having a readily available home test could increase pressure on NHS resources, with more couples identifying problems at an early stage.
"It might do that. People will get a quicker answer and think they need to act more quickly and seek treatment," he said.
"But we are thinking about the benefit to the patient. Early detection is the real key because time is of the essence and fertility does decrease with age, particularly with men over 35."
The kits are due to go on general sale from January 9, but are already available in some larger Boots stores.