NEW YORK • Mr Gilbert Sanchez froze his sperm in January, shortly before his 25th birthday.
He was healthy and at low-risk of fertility issues. But he wanted to be pro-active - just as thousands of young women have been by putting their eggs on ice.
"It was a little bit weird," admitted Mr Sanchez, who stored his sperm with a company called Legacy. "But it was medically responsible."
His choice highlights a new anxiety about sperm health among American men.
The idea that men can easily father healthy children into their 70s and 80s has been exposed as a myth.
Research shows that older men have a higher risk that their partners will miscarry and have children with congenital abnormalities, schizophrenia or autism.
New businesses are capitalising on those revelations. Start-ups like Trak, YO sperm and SpermCheck are selling at-home testing kits so men can figure out early if there is something amiss with their sperm.
Legacy, based at the Harvard Innovation Labs that launched last October, is part of a new breed of sperm-freezing outfits that aim to shake up the industry by offering mail-in kits that allow the whole process to be done in the privacy of one's home.
A competitor, called Dadi (pronounced "daddy"), launched at the end of January.
Its message is that sperm freezing should not just be for men suffering from infertility, cancer or heading off to a war zone.
Mr Tom Smith, Dadi's chief executive, argued that "men have a biological clock just like women. This gives them the option to start a family when the time is right for them".
But some believe sperm freezing for the masses is overkill.
Ms Tracey Woodruff, who directs the Programme on Reproductive Health and Environment at University of California in San Francisco, said concerns about male infertility should be focused on preventing the issues in the first place - for instance, with sturdier regulations of substances affecting male reproduction.
Dr Natan Bar-Chama, a male infertility specialist at Reproductive Medicine Associates of New York, said: "A normal healthy male in his 20s and 30s - we don't recommend it. If we're talking about someone in his 40s, who thinks he is not going to have children until he is in his 60s, it's up for discussion."
Women have been the focus of talk about the "fertility cliff" and pregnancy troubles for so long that it is easy to forget the men.
The reality is that male factors are at play in 30 to 50 per cent of cases of couples having infertility trouble - and nearly all those cases are related to sperm.
But egg freezing and sperm freezing involve wildly different risks and expenses.
Egg freezing involves an invasive, multi-week process of hormone injections and a surgical procedure that can cost US$10,000 (S$13,600) to US$15,000. It usually yields anywhere from six to 12 eggs.
Sperm freezing is much simpler and less expensive.
Under Legacy's service, a man orders a kit online and puts a sample into a container, mixes it with a preservative and mails it back to the company.
Clients are assigned a number that is used to label the samples and communicate with the company.
Everything is encrypted.
The sample - which would typically contain millions of sperm - is tested and a report is sent to the customer on the health of the sperm.
The lab splits the semen into different "straws" to be stored in two separate cryotanks in two locations in the United States.
The cost of sperm freezing can vary a great deal.
If you do it in a fertility centre, it can sometimes cost more than US$1,000 for the collection and testing.
Legacy's mail-in packages start at US$350 for one "deposit" and US$20 a month for storage.
Dadi uses one storage facility, but its cost is significantly cheaper - an initial US$99 fee for the collection kit and test, plus US$9.99 a month or US$99 annually for storage.
Legacy and Dadi declined to reveal the number of sales so far but Legacy said clients are from all across the US.
They are typically in their 30s to 40s, with Mr Sanchez, a project manager from Phoenix, among the youngest.
Many have stories like Rami, a 26-year-old who works in the tech industry in San Francisco, and who asked that his last name not be used.
He decided to freeze his sperm earlier this year because of his older friends' struggles with infertility.
"I knew the pain they went through," he said.
Meanwhile, many women - wives, girlfriends, sisters, mothers - have seized on sperm freezing as a sign of reproductive equality.
"It makes the discussion more complete," said Ms Anna Barnacka, 35, chief executive of a Boston-area company.
"Men and women both have issues with fertility. It's not just one side."