
But the new standard suggests that the inability to find a suitable sexual partner – or the lack of sexual relationships which could achieve conception – could be considered an equal disability.
The World Health Organisation sets global health standards and its ruling is likely to place pressure on the NHS to change its policy on who can access IVF treatment.
Legal experts said the new definition, which will be sent out to every health minister next year, may force a law change, allowing the introduction of commercial surrogacy.
However the ruling is also likely to lead to accusations that that the body has overstepped its remit by moving from its remit of health into matters of social affairs.
Under the new terms, heterosexual single men and women, and gay men and women who want to have children would be given the same priority as couples seeking IVF because of medical fertility problems.
Dr David Adamson, one of the authors of the new standards, said: “The definition of infertility is now written in such a way that it includes the rights of all individuals to have a family, and that includes single men, single women, gay men, gay women.
"It puts a stake in the ground and says an individual's got a right to reproduce whether or not they have a partner. It's a big change."It fundamentally alters who should be included in this group and who should have access to healthcare. It sets an international legal standard. Countries are bound by it."