The words 'mother' and 'father' are to disappear from birth certificates to allow homosexual couples to be named as 'parents' of surrogate children.

The switch means the biological parents will no longer necessarily be identified on the certificates that provide a legal record of a child's birth.

Birth certificates have recorded mothers and fathers since registration of babies was introduced more than 170 years ago.

The words 'mother' and 'father' are to disappear from birth certificates to allow homosexual couples to be named as 'parents' of surrogate children

But to comply with a change in the law, around 200 special certificates a year will be authorised for same-sex couples who qualify under a new
law as the legal parents of a child born through surrogacy or fertility
treatment.

The move has been questioned by fertility experts and lawyers, who believe it means birth records will be effectively falsified.

In the case of two women who register as the parents of a child, there will be no record on the birth register of who the biological father is.

Baroness Deech, a former head of the Human Fertilisation and Embryology Authority, warned: 'It could even result in deception to exclude the natural father where the mother
conceived naturally but uses this provision to cut him out of the
child's life.'

But gay pressure groups have welcomed the move.

Ben Summerskill, of Stonewall, said: 'We are delighted that the reality of people's family lives in being recognised at last, that lesbian and gay
couples no longer have to go through the unpleasantness of an adoption
procedure.

'The law means that from next week, two men who have a child by a surrogate mother will be able to apply to a family court for an order making them the legal parents. The court will rule on whether
they are fit to bring up the child.

In this case an original birth certificate naming the mother will exist. But it will be replaced by a new document naming the two men as parents if a judge grants a
parental order.

A child will be able to trace the original birth certificate once he or she is 18 years old.

Rules governing the issue of certificates have been strictly upheld since 1837, the year Queen Victoria came to the throne.

Registrars must, for example, record entries on certificates in the same kind of ink developed in the 1830s to ensure it does not fade or be easily erased.

Lady Deech, a senior family lawyer, said the rule allowing two parents of the same sex to appear on birth certificates gave her 'unease'.

She said: 'There is an issue of principle here, which is the truth.

'It puts the demands of the adults ahead of the rights of children to know and benefit from both sides of their genetic makeup.'