Mens hormones go into a spin in the months before their first child arrives.

London - Male fertility problems are behind the vast majority of cases where a couple are unable to conceive, a study has found.

Each year, 50,000 couples are warned they require fertility treatment but up to a third are told by doctors that no problem can be detected.

But a study has found that 80 percent of couples with unexplained infertility cannot conceive because of poor sperm quality, known as high sperm DNA damage.

Now a test has been developed to detect the condition and measure its extent, allowing would-be parents to move on to the treatment most likely to succeed.

Most fertility clinics judge sperm quality by looking at its shape, speed and concentration under a microscope.

The new test checks for tiny breaks and tears in the sperm’s DNA. Sperm damaged in this way is less likely to make a woman pregnant and, if she does conceive, she is more likely to miscarry.

A study by Professor Sheena Lewis, of the School of Medicine, Dentistry and Biomedical Sciences at Queen’s University Belfast, looked at 239 couples with unexplained infertility. It found that 80 percent had a detectable cause of infertility in the form of high sperm DNA damage.

Professor Lewis, a member of the executive committee of the British Fertility Society, said prompt and appropriate treatment could save money, heartache and – crucially – time.

She added: “For almost one third of couples, until now, there has been no obvious cause for infertility and these couples are given the diagnosis of ‘unexplained fertility’. These couples often invest a lot of time and money in fertility treatments, like intrauterine insemination, which are unlikely to be successful.

“Now that we have found the cause of infertility for these couples suitable treatments can be tailored which will direct them straight to the best treatment and increase their chances of having a baby.” - Daily Mail