When it comes to the the size of a male's manhood, it appears size really does matter.

Men with smaller penises tend to be less fertile, a new study has revealed.

Those with fertility problems tend to have penises around a third of an inch shorter when erect, on average, than men without any issues.

Men with smaller penises tend to be less fertile, a new study has revealed. File photo

The study researched 815 men going to a sexual health clinic over a span of three years.

According to the data collected, men who were infertile had an average length of 4.92in compared to fertile men with 5.27in.

Study leader Dr Austen Slade of the University of Utah, Salt Lake City, said: 'It may not be a striking difference but there was a clear statistical significance.

'It remains to be determined if there are different penile length cut-offs that would predict more severe infertility.'

Dr Slade said shorter penises could hint at problem with fertility but added it was nothing to be worried about.

He said: 'For now, men with shorter penises don't need to worry about fertility.'

According to the data collected, men who were infertile had an average length of 4.92in compared to fertile men with 5.27in. File photo

The findings were presented at the world's biggest fertility conference in Denver, Colorado, US.

But Prof Sheena Lewis of Queen's University in Belfast said: 'One thing that scares men is that size matters.

'To now say they have a smaller chance of becoming a father is not a good message.'