Europe Wants a 50-Family Cap on Sperm Donors. Is That Enough?

At its July 8 conference in London, the European Society of Human Reproduction and Embryology (ESHRE) called for a cap of 50 families per sperm or egg donor across Europe, with a stated goal of eventually tightening that to 15 families. The proposal follows years of cases in which donor-conceived people have discovered hundreds of genetic siblings, sometimes only after a shared biological parent has died. One Dutch donor's sperm was used to conceive between 550 and 600 children before a court intervened in 2023. ESHRE acknowledges enforcement will be difficult, especially given the international sperm trade.

What happened

Detail	Fact
Event	ESHRE annual meeting, London, July 8, 2026
Initial proposed cap	50 families per donor
Long-term target cap	15 families per donor
UK current limit	10 families per donor
Denmark current limit	12 families per donor
Malta and Cyprus limit	1 child per donor
UK imported donations (2020)	More than 50%, mostly from Denmark and the US
Jonathan Meijer children conceived	550 to 600
Danish donor cancer case	Sperm used to conceive at least 197 children across Europe

ESHRE, the main European body for reproductive medicine specialists, used its London conference to formally call on fertility clinics and sperm and egg banks to respect a limit of 50 families per donor. That figure is meant as a starting point. Professor Jackson Kirkman-Brown, a reproductive biology researcher at the University of Birmingham who led the months-long process of drafting ESHRE’s position document, said the group wants to push that number down to 15 families per donor over time.

Kirkman-Brown’s team consulted fertility specialists, clinics, sperm and egg banks, donors, and donor-conceived people before settling on those numbers. Even so, several people at the meeting told MIT Technology Review that 50 is still very high. Vasanti Jadva, who studies the psychological well-being of people conceived through donated eggs, sperm, and embryos at City St George’s in London, noted that researchers still do not know what the right number is. “We may find that 15 is also too high,” she said.

Why the current system produces hundreds of siblings

Frozen sperm can be stored and used across many years and many countries. A single donor who meets screening requirements can, without any central registry tracking outcomes, contribute to far more births than any one clinic knows about. Jonathan Meijer, a Dutch man who started donating in 2007, had his sperm used to father between 550 and 600 children before a Dutch court ordered him to stop in 2023. Stichting Donorkind, an advocacy foundation for donor-conceived people chaired by Ties van der Meer, brought that case to court.

The genetic testing industry has made the scale of these situations visible in a way it never was before. Services from companies such as Ancestry and 23andMe, combined with genetic registries, now allow donor-conceived people to find biological relatives they were never told about. One woman who used these tools found 25 half-siblings over seven years. Others have found hundreds.

There is also a documented medical risk. A man who donated to a Danish sperm bank was later found to carry a genetic mutation that significantly increases the risk of multiple cancers. His sperm had already been used to conceive at least 197 children across Europe. Some of those children developed cancer. Some died.

Why national limits alone do not solve the problem

Most countries with active fertility industries already set donor limits, but those limits apply only within their own borders. Denmark caps donations at 12 families, yet Denmark is one of the largest exporters of donor sperm in the world. In 2020, more than half of sperm donations used in the UK were imported, with Denmark and the US as the primary sources. A donor who has reached the Danish family limit could have sperm in storage abroad that continues to be used.

“The only thing that really makes sense is a transnational limit,” Kirkman-Brown said at the meeting. The document ESHRE released represents its formal position, but the organization cannot compel governments to act. Enforcement will require cooperation between national regulators, clinics, and banks across multiple jurisdictions, none of which currently share real-time data on donor outcomes.

What about the US?

When MIT Technology Review asked the American Society of Reproductive Medicine for a response to the ESHRE proposal, a representative pointed to existing guidance. That guidance says it has been suggested that for a population of 800,000, a single donor should be limited to no more than 25 births to reduce the risk of close relatives unknowingly forming relationships. Many US sperm banks voluntarily cap single-donor families at around 25, but there is no federal law requiring it. Given that the US population exceeds 340 million, a straight extrapolation of that 800,000-to-25-births ratio would produce a very large total ceiling.

Our take

This is a straightforward case where technology moved faster than regulation. Genetic testing made the problem visible; international commerce made it hard to fix. The ESHRE proposal is a reasonable first step from a professional body, but a voluntary guideline asking clinics to cap at 50 families is not the same as an enforceable law, and 50 families is still a very high number by any standard of what most people would consider reasonable.

Van der Meer, who was himself donor-conceived and who chairs the advocacy group that took Meijer to court, reportedly thinks even five families from a single donor would be a more appropriate ceiling. That is a very different number from 50. The gap between what affected people think is acceptable and what the fertility industry is being asked to accept tells you something about where the power sits in this debate.

There is also an honest supply-side risk: if limits tighten without a parallel effort to recruit more donors, some prospective parents will turn to unregulated donations. Unregulated donors skip health screening, and they can later seek parental rights over children conceived with their sperm. Tighter regulation without adequate donor recruitment could push demand into a less safe channel. That tradeoff deserves more attention than it is currently getting.

For anyone building products or services in the health or fertility space, this story is a reminder that AI-assisted data matching and genetic registries are now central to how people navigate identity. The regulatory conversation will follow. Staying ahead of it matters. You can also follow our broader AI and technology news coverage for related developments in biotech and data policy.

What to do about it

1. If you were donor-conceived, check whether the clinic that treated your parent kept records, as the Netherlands banned anonymous donation in 2004 and practices varied before that.
2. Use genetic registries and consumer DNA testing services to locate biological relatives if you want to, knowing that results may surface unexpected family sizes.
3. If you are a fertility clinic or sperm bank operator, review the ESHRE position document released at the July 8 London meeting and assess how your donor tracking aligns with the proposed 50-family initial cap.
4. Advocate for your national regulator to join any future transnational data-sharing system, since national limits alone cannot close the cross-border gap.

The right number of families per donor is still genuinely unknown. Push your clinic or bank to explain exactly how they track it, across borders, right now.

Source: MIT Technology Review