The number of sperm donations has fallen to the lowest level on record after donors' right to anonymity was removed, official figures have shown.
Figures obtained by the Times reveal that the number of women treated with donated sperm fell by around a fifth between 2005 and 2006.
This suggests that the fall in donations is hindering women's ability to access infertility treatment.
Dr Allan Pacey, secretary of the British Fertility Society, told BBC Radio 4's Today programme that the actual number of male donors does not appear to have declined, but that donors are placing restrictions on the number of women who can receive their sperm.
While the law allows an individual's sperm to be used by up to ten women, many donors are now stipulating a lower number of women or naming a specific female friend who can use their sperm.
"After the law change, men were more reluctant to allow a greater number of women to receive treatment," Dr Pacey claimed.
"Couples are bringing a friend of the family as their own donor and that donor is only giving the donation specifically to them."