Single women and lesbian couples won landmark parental rights last night as MPs voted to remove the requirement that fertility clinics consider a child’s need for a father.

The Human Fertilisation and Embryology Bill will replace the rule with a “need for supportive parenting” after opponents were defeated in two votes by unexpectedly wide margins.

The Government had been prepared for defeat but won the free votes by majorities of 75 and 68. The decisions mean that the legislation will grant the most significant extension to homosexual family rights since gay adoption was sanctioned.

It will stop fertility clinics turning away lesbians and single women because their children will not have a father or male role model. While the current law does not block such therapy, it is sometimes used to justify refusals.

In another landmark decision last night, MPs rejected moves to prevent women having abortions up to 24 weeks into pregnancy. In the first vote on the issue in 18 years, an attempt to reduce the limit to 22 weeks was rejected by 71 votes. An attempt to reduce the limit to 20 weeks was defeated by a majority of 142.

The defeat came despite a high-profile cross-party campaign and the decision by David Cameron, the Conservative leader, to back a reduction in the limit to 20 weeks. The Prime Minister voted to retain the existing limit.

The Government has now won all four of the measures on which it agreed to grant Labour MPs a free vote. Moves to allow the creation of hybrid embryos for medical research, and “saviour siblings” screened as suitable tissue donors for sick children, were passed by large majorities on Monday.

MPs who backed the fatherhood amendments said the traditional family would be undermined. Iain Duncan Smith, who proposed enshrining the importance of a father and mother, said that the new law would amount to telling couples that “fathers are not important, or are less important than mothers”.

The former Tory leader said there was overwhelming evidence that children without fathers were more likely to have problems at school and with drink and drugs. He also questioned whether the existing law led to genuine discrimination, as many IVF clinics already treated lesbians and single women.

His criticisms were backed by Cardinal Cormac Murphy-O’ Connor, the Roman Catholic Archbishop of Westminster, in an interview with The Times. “I think it strange that the Government should want to take away not just the need for a father but the right for a father,” he said.

The law will now be brought into line with the Human Rights Act. The Bill will also allow both partners to be recognised as parents when lesbian couples conceive with donated sperm, or gay men use surrogacy. At present, only the natural mother or father is automatically considered to be a parent when gay couples have fertility treatment.

A Times/Populus poll last month found that 40 per cent of people were against the Government’s proposals and 32 per cent in favour. It also revealed a generational divide: while over-55s were strongly opposed, 18 to 34-year-olds were strongly in favour of reform.

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