Size really does matter when it comes to fertility

The study is the first of its kind to identify an association between shorter penile length and male infertility - Science Photo Library RF
The study is the first of its kind to identify an association between shorter penile length and male infertility - Science Photo Library RF

Size really does matter when it comes to fertility as a new study suggests men who are infertile are also less well endowed.

Having a shorter appendage was more common in men who were struggling to conceive than in those with other genital health problems. The research, to be presented at the American Society for Reproductive Medicine conference in Colorado this week, is the first ever to link penile length with fertility.

It found that on average, men who were infertile were around one centimetre shorter than their fertile counterparts. Those without reproductive issues had an average length of 13.4 cm while those in the infertile group were 12.5cm.

Dr Austen Slade from the University of Utah, Salt Lake City who led the study, said healthy men should not begin to fret over their size and their chance of becoming a father. Instead, he said underlying conditions that caused infertility, such as hormonal issues or problems in the testes, may also lead to a shorter penile length.

“This is the first study to identify an association between shorter penile length and male infertility,” he said. “It's possibly a manifestation of congenital or genetic factors that predispose one to infertility. For now, men with shorter penises don't need to worry about their fertility.”

The study looked at data on 815 men visiting a Men’s health clinic between 2014 and 2017. There were 219 men seeking help for infertility and 596 seeking help for other conditions such as erectile dysfunction and testicular pain.

The men were all measured using a standard test called ‘Stretched Penile Length’ that estimates length when erect. When they took into account weight, race and age, those being treated for infertility were just under one centimetre shorter than those who were fertile. “One centimetre 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 added.

Previous research has shown that physical problems with male genitals can impact on fertility. Men with a condition called cryptorchidism – where the testes do not descend properly – have poorer sperm production. This is because the testes are located too close to the body, allowing the sperm to become too hot. Men with small testes have also been found to produce less sperm.

Professor Sheena Lewis, an expert in reproduction from Queen's University. Belfast said that although the study was interesting, it raised more questions than it answered. “We give men such a bad press all the time and the one thing that scares them is that size matters  To now to say they have a smaller chance of becoming a father is not a good message. This is also a problem you cannot find a solution to – what can you do about it? 

"Also doctors would not want to measure this in clinic, so as a study the findings are not really clinically usable. This is a very novel idea but study does not tell us what a normal penis length is.  It does not say if the shorter penis found in the study is abnormal and more research is needed."

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