When Mick Jagger’s youngest child, Deveraux Octavian Basil Jagger (seriously), was born in 2016, the aging rocker was already a septuagenarian. That’s notable, because – and bear with us, we know this is controversial – having babies in your 70s is weird. We’re not making a moral judgment here: at more than six standard deviations from the mean, he was without a doubt one of the oldest people on the planet to have a new baby that year.
But as science marches on – and legislation scurries to catch up behind it – even seemingly self-evident facts like “men who want children should conceive before the age of about 45” get outdated. Thanks to a recent change of law in the UK regarding the length of time frozen sperm can be stored, future dads may be older than ever when their babies are born – and experts suggest there’s no scientific reason that limit couldn’t be extended even further.
Using frozen sperm for conception goes further back than you might think: the first live birth from cryopreserved semen was reported in 1953. Back then, sperm could only be stored for short periods of time – but by the early 60s, technology had moved on enough that long-term cryopreservation was an option. In fact, the techniques were already so effective that, in 2012, twins were born from IVF using frozen sperm from 40 years prior.
Despite this seminal longevity, until recently, sperm, egg, and embryo cryopreservation in the UK was generally limited to just 10 years. That changed in July this year, when lawmakers raised the limit to 55 years, citing the soaring popularity of such procedures and improved information about the link between fertility and age.
“Every person should be given the best possible opportunity to start a family, which is why it is so important that our laws reflect the latest in technological advancements,” said Caroline Dineage, at that point the Minister for Care and Mental Health, in a February 2020 statement preceding the decision.
“Although this could affect any one of us, I am particularly concerned by the impact of the current law on women’s reproductive choices,” she added. “A time limit can often mean women are faced with the heart-breaking decision to destroy their frozen eggs, or feel pressured to have a child before they are ready.”
Now, 55 years sounds like a pretty specific cut-off, so you’d expect there to be some solid science behind it. But in fact, experts say there’s no reason much older sperm couldn't be used – and in theory, super-progenitors like Jagger could still be fathering babies centuries into the future.
“The legal 55-year limit has nothing to do with the shelf life of sperm, or for any other scientific reasons. It’s more to do with what parliamentarians felt was right for society,” Allan Pacey, a professor of andrology at the University of Sheffield, told The Guardian.
“But since frozen sperm are effectively in suspended animation, once they are frozen I don’t see why they couldn’t be kept for hundreds of years if the law allowed it,” he said. “Sperm from prize bulls [is] kept in storage for much longer than we typically keep human sperm for, without any obvious problem.”
But just because it’s theoretically possible, doesn’t mean it’s likely to happen. It’s true there’s little evidence of danger from super-aged sperm, but outside of livestock, there’s also not much in the way of evidence in the other direction. Cases of IVF using sperm frozen for many decades are few and far between – only last week, a newborn made headlines in the UK after being born using sperm from 1996, and babies of similar vintages are still rare enough to stand out as notable even in recent years.
Which is a problem because there’s a lot that needs to be studied if older sperm is to become more common. What, for example, would be the emotional impact of being born to an extremely old or even deceased father? What would be the impact, if any, on personal and public health, if a bunch of children started being born with a sizeable chunk of DNA which originated centuries earlier?
“We’re really doing an experiment, and I’m in favour of those,” Julian Savulescu, an ethics professor at the University of Oxford told The Guardian. “But you have a moral obligation to generate knowledge and modify practice according to the results.”
Luckily, we’ve time to figure these things out, Savulescu pointed out. Even the oldest frozen sperm can only be a few decades old at this point, so problems associated with centuries-old samples are not much more than “science fiction worries,” he added.
Of course, that’s in humans. When it comes to Jurassic Park, the ethical dilemmas are only just beginning.