Lesbian parents can both be called mother

London: The concept of a two-mother family is to be enshrined in law for the first time.

The Human Tissues and Embryos Bill, to be announced in the Queen's Speech next week, will give both women in a lesbian relationship the legal status of parents when one of them gives birth following fertility treatment.

Experts say this marks a historic change in how a family is legally defined.

The change was condemned by family campaigners as a "dangerous social experiment" but supporters said it was "logical and just".

The Bill lays down that where two women are in a relationship and one has fertility treatment in order to conceive then the partner should be treated as the other "parent" even if they are not in a civil partnership. In those circumstances no man - such as the sperm donor - can be treated as a father, the Bill says, to avoid a child having three legal parents.

The change reflects the fact that in a heterosexual couple when the women is inseminated with donor sperm the man is treated as the father even though he has no biological link to the resulting child.

The Bill says that where there is reference to the father of a child such as on birth certificates this is to be read as reference to the female parent who did not give birth.

It will also say for the first time that babies born through fertility treatment do not need to have a father figure and parents will be banned from choosing the sex of their child.

Evan Harris, a Liberal Democrat MP, said: "This is a logical and just consequence of the civil partnership provisions overwhelmingly supported in both houses of Parliament."

No substitute

But campaigners said there was no substitute for a family unit in which children are brought up with input from both mother and father.

Norman Wells, of the Family Education Trust, said: "We are embarking on a dangerous social experiment with serious consequences for individual children and for society as a whole when we start tampering with the natural order and deny children something as fundamental as having a parent of each sex."