The figures indicate that each donor has biologically fathered children in at least ten separate instances. Furthermore, fifteen donors have successfully fathered twenty or more children. The HFEA has refused to reveal the highest number of children born to a single sperm donor, however, on grounds that it may result in a breach of the confidentiality provisions of section 33A of the Human Fertilisation and Embryology Act 1990 (as amended), and the information was therefore exempt from disclosure under section 44 of the Freedom of Information Act 2000.
The data is drawn from records of IVF and other fertility treatments gathered by the HFEA from clinics across the UK. Current laws restrict the use of sperm from each donor to ten different families (excluding their own), however there is no limit set on the number of children born into each family.
Donors who donate through a licensed fertility clinic acquire no legal rights or responsibilities towards any resulting children, but after a change in the law in 2005 donor-conceived children now have the right to receive identifying information about their biological parents once they reach the age of 18.
Current estimates show that approximately 1,000 children are born every year in the UK with the help of sperm donation.