‘Fertility preservation’: Men freezing sperm to turn back their biological clocks
“Social sperm freezing” is on the rise among men rattled by growing science that postponing fatherhood increases the risk their sperm will carry disease-causing mutations that will be passed on to their child.
While there’s no clear consensus as to when a man becomes biologically “old,” most studies are now putting “advanced paternal age” at 40 and older.
Meanwhile, evidence is mounting that the sperm of older men increases the risk of stillbirths, birth defects, certain childhood cancers, autism and schizophrenia. A landmark 2012 study found a 36-year-old man will pass on twice as many mutations to his child as a man of 20; a 70-year-old, eight times as many. One bioethicist warned in 2015 that the trend of later fatherhood, and the accumulation of paternal-driven mutations in the gene pool, threatens the fitness of the human race.
While no one is collecting the figures, Canadian reproductive specialists say they are seeing an increase in men freezing sperm for later use. At the Toronto fertility clinic ReproMed: The Toronto Institute for Reproductive Medicine, demand has doubled year-over-year for the past five years.
Men seeking to cold-store semen range from their mid-20s to mid-40s. Some are worried about declining sperm quality, others about passing along DNA defects to their children.
“I would hesitate to refer to this as ‘social sperm freezing,’” Dr. Tamer Said, director of ReproMed’s andrology lab and sperm bank, said. “Perhaps the term ‘fertility preservation’ could offer a more accurate description.”
Still, experts are debating whether men should even be freezing sperm for later use. While growing numbers of Canadian women are seeking “social egg freezing” — a once highly experimental procedure that allows women to put their younger and more fertile eggs in cold storage until they’re ready to try to have a baby — the issue is more nuanced in men.
“With egg freezing, it’s, ‘If you don’t do this, there is a chance you might never have your own biological children,’” said Dr. Heather Shapiro, past president of the Canadian Fertility and Andrology Society and vice-chair of education in the University of Toronto’s department of obstetrics and gynecology.
“With sperm freezing, it’s, ‘If you don’t do this, there is a chance that your biological child might be at risk for some as-yet-determined condition at some as-yet-determined frequency,” Shapiro said.
“And so some people would say that’s enough of a question mark for me to make me do it.”
Men don’t fall off a fertility cliff the way women do at menopause. For males, the decline is more gradual and subtle. Aging affects semen volume, motility and morphology — instead of swimming fast and forward they spin around in circles, or have more than one head. Studies have shown age-related changes as early as 35.
“The majority of men are going to stay fertile their whole lives,” said Dr. Michael Jennings, co-author of one of several articles in this month’s issue of Fertility and Sterility on older dads, and whether there should be upper age limits for medically assisted fatherhood, the way there are for women. “There are 90-year-old (men) who can conceive children,” said Jennings, a third-year resident at the University of Tennessee Medical Centre.
In December, Rolling Stones front man Mick Jagger became a father again, at 73. This week, news broke that George Clooney, 55, and his 39-year-old wife Amal are expecting twins in June.
Jennings and senior author Dr. Edward Kim argue it’s difficult to recommend young males bank sperm just to offset “the deleterious effects” of aging on semen.
For one thing, the freeze-thaw process itself could affect sperm quality.
“You have to balance the risks — yes, there may be an advantage to banking sperm when you’re 20 because you’re not sure when you’re going to have children,” said Dr. Amand Zini, professor of surgery at McGill University in Montreal.
“But, will it truly be better than what you have when you’re 40? I don’t know that we have good answers for that.”
Then there are the costs — roughly $200 to $500 to initially freeze a sample and up to $400 in annual storage fees.
As well, the increased risks to children attributed to older fathers are low, in absolute terms. According to a review of the epidemiological evidence published in Fertility and Sterility, “the adverse health effects in children … are severe but quantitatively of minor importance.” (One study even suggested older men have less attractive children. According to The Telegraph, University of Vienna researchers who asked volunteers to rate the attractiveness of more than 8,000 men and women concluded “the subject’s facial attractiveness decreased with advancing paternal but not maternal age, suggesting that facial attractiveness might be a cue of an individual’s new mutation load.”)
Will it truly be better than what you have when you’re 40? I don’t know that we have good answers for that
Social sperm freezing could also raise ethical and legal issues, including who decides the semen’s fate if the man dies before it’s used.
“I’m not sure a 20-year-old would be ready to accept this,” said Zini, of McGill, who has helped men in their upper 60s (newly married to much younger women) conceive using their own sperm. “It’s still too early to say this needs to be done, or offered routinely.”