Men are putting their fertility on ice as sperm quality plummets after the age of 45. (AP Photo/Mark Schiefelbein)

Men have long been able to freeze their sperm before they undergo treatment for conditions such as cancer that can affect fertility. 

But, just as each year hundreds of women pay to put their eggs ‘on ice’ until they are ready to start a family, men are now following suit with their sperm.

The numbers are small, but experts expect them to rise as men become more aware of the fact that it is not just women who have a ‘biological clock’.

‘Freezing sperm is a lot easier than freezing eggs,’ says Professor Geeta Nargund, medical director of Create Fertility, where Maxwell is a patient. ‘You don’t have to undergo a clinical procedure, you don’t have to take any fertility drugs and it’s a lot cheaper, so I think it will become much more common.’

More women freeze their eggs each year and it’s thought that most of those are doing it in order to put fertility on hold, rather than for any medical reason.

Andrology Solutions in London, which specialises in male fertility, is one clinic already freezing sperm — predominantly for professional single men, typically in their 40s, who worry their age may hinder their chances of fatherhood.

‘Just like women, there are plenty of men who want a family, but haven’t yet found the right partner,’ says Dr Sheryl Homa, the clinic’s scientific director.

‘Men have as much a biological need for children as women, and they want healthy children.’

Clinics typically store the sperm for ten years, unless the man becomes infertile during that time, in which case their sample can be kept for up to 55 years.

Not only does men’s fertility drop as they get older, as factors such as smoking, drinking and bad diet, as well as age-related illness including diabetes, take their toll on the body, but older fathers — just like older mothers — risk having less healthy babies.

In the latest study, published in The BMJ in November last year, researchers at Stanford University in the U.S. analysed health records involving 40.5 million births between 2007 and 2016.

It revealed that babies born to older fathers were more likely to be premature, have a low birth weight, experience seizures and need intensive care after birth, compared with babies born to younger fathers.

The risk of complications started to increase when the men hit their mid-30s and rose sharply from the age of 45.

With fathers aged 45 or older, there was a 14% greater risk of babies being born prematurely or being admitted to a neonatal intensive care unit and an 18% greater risk of suffering from seizures, compared with infants born to fathers aged 25 to 34 years.

Men aged 50 or older were 28% more likely to have a child that required intensive care than those born to younger fathers.

The theory is that the production of sperm becomes more error-prone as men age, leading to genetic mistakes creeping into the sperm’s DNA, with associated health risks for future children.

Previous research has linked having an older father to a host of other ills, including a higher risk of heart defects, epilepsy and mental illnesses including schizophrenia, as well as some cancers.

DNA damage to sperm also makes it harder for embryos to implant in the womb, so women with older male partners take longer to conceive and are more likely to miscarry.

Research shows that children born from sperm that has been frozen are just as healthy as other babies. However, freezing and thawing is such a brutal process that only around 40% of sperm will survive it.

Professor Sheena Lewis, an expert in male fertility from Queen’s University Belfast says male celebrities who have children late in life send ‘the most horrendous message to men at large’.

Sir Mick Jagger was 73 when his son Deveraux, his eighth child, was born in 2016.