So Mick Jagger is to be a father for the eighth time at the age of 73. The announcement that his 29-year-old girlfriend is expecting has led to some internet ribbing.
Certainly the Rolling Stones discography offers an opportunity to have fun at the lead singer's expense. Clearly 'Start me Up' isn't a problem for the 'Jumpin' Jack Flash' of rock.
With bandmate Ronnie Wood the recent father of twins at the age of 68, the sex, drugs and rock'n'roll lifestyle hasn't affected the Rolling Stones' collective fertility. Are Jagger and Richards bucking the trend of male fertility?
A woman’s fertility begins a noticeable decline after age 35; by 40 she has a 5 per cent chance of getting pregnant per menstrual cycle.
It’s a different story for men, with sperm quality not usually a barrier to conception before a man hits his 60s.
But there is evidence of an earlier decline: in one study men older than 35 years had half the chance of fathering a child within 12 months compared with men aged less than 25 years, after controlling for women’s age and other factors .
Semen quality is generally considered to be a proxy measure of male fertility.
Research suggests that age is associated with diminished semen volume, sperm motility and sperm morphology.
For example, the probability for having abnormal sperm motility is approximately 52 per cent at age 30 years, 67 per cent at age 50, and 84 per cent by age 80. And it seems the sperm of older men have a slightly higher risk of gene defects.
One study found that children born to men over the age of 45 were three-and-a-half times more likely to be diagnosed with autism and 13 times more likely to be diagnosed with ADHD than babies born to men aged 20-24.
The best sperm quality is found in men who have never smoked and never drank alcohol.
A history of high blood pressure, on the other hand, takes the shine of a man’s sperm.
While more recent British research found that smoking cannabis can have a severe effect on male fertility, other lifestyle choices such as drinking alcohol and wearing tight briefs were not a barrier.
So while the booze-laden lifestyle of the Stones may not have damaged the band members’ fertility, it’s a good bet that any illicit drug taking did.
And as testicular space was at a premium in their stage outfits, this won’t have helped.
Meanwhile can we make any inferences about Jagger’s and Wood’s lifestyle from their impressive fertility?
It’s a fair bet they consume a lot of red fruit and vegetables. Lycopene containing tomatoes, strawberries, cherries and peppers have been shown to increase sperm count by as much as 70 per cent.
And they are probably not fans of hot baths either.
The ideal temperature for sperm production is 34.5 degrees celsius, which is slightly below body temperature.
A US study showed that five out of 11 men who stopped taking hot baths experienced a sperm count rise of almost 500 per cent.
The jury must remain out on whether the Stones members are keen coffee drinkers.
While one study showed drinking coffee increased the swimming speed of sperm, another suggests imbibing just 3 cups of joe a day can cause genetic mutations in sperm.
But we can be fairly certain that neither Jagger or Woods is a keen cyclist; excessive time in the saddle has been shown to affect the shape and size of sperm.
There appears to be a paucity of research into the contribution of young female eggs to older men’s fertility, something that could be a factor in these ageing rockers’ recent adventures.
Meanwhile ‘Diddley Daddy’ Mick cannot but hope that ‘Time is on (his) Side’ to witness his youngest child grow up. His legion of fans will presumably have ‘Sympathy for the (old) Devil’.