Sperm donation is apparently a grueling and exacting process through which not many men emerge.

Fewer than four out of every 100 men who apply to be sperm donors actually wind up providing a sample that’s used in fertility treatment, a new study reports.

The rest either give up or wash out, according to findings reported Jan. 9 in the journal Human Reproduction.

For the study, researchers tracked the outcomes of more than 11,700 Danish and American men who applied to be donors to Cryos International, one of the world’s largest sperm banks.

“The study with Cryos highlights how hard it is to become a sperm donor,” said lead researcher Allan Pacey, head of oncology and metabolism with the University of Sheffield in the UK. “It’s not like blood donation, where once it’s done you can have a cup of tea and go home. Sperm donation is a regular commitment with lots of screening and regular testing as well as lifelong implications for the donor if any children are born from their sample.”

Nearly 55% of potential donors were lost during recruitment, researchers found. They either withdrew their application, failed to respond, or stopped showing up to appointments.

Nearly a fifth (17%) were rejected on medical grounds. They either had a health issue, carried a genetic disease or had an infectious disease that could not be treated.

Just over one in 10 (12%) failed a screening questionnaire about their lifestyle, and another one in 10 (11%) were rejected due to poor sperm quality.

Only 3.8% of applicants were accepted as donors, had samples frozen, and then had those samples released for use, researchers said.

The UK researchers also looked at whether donors would be willing to waive their anonymity. Since 2006, it’s been illegal in the UK to use sperm from donors who are unwilling to be identified to offspring born from their donations.

They found that initially about four in 10 donor candidates agreed to be identifiable. Applicants in Denmark more commonly waived anonymity than U.S. applicants.

However, as the screening and donation process continued, more of the donors who initially wanted anonymity agreed to become identifiable, researchers said.

More information

The University of California, San Francisco has more about sperm donation.

SOURCE: University of Sheffield, news release, Jan. 9, 2022