The bulk of the Shadow Cabinet voted in favour of an amendment that would have retained a requirement on doctors to consider the need for a father when assessing women for IVF treatment.
The government argued that the consideration has been used to disciminate against lesbians and single women, and they defeated the amendment, which was proposed by former Tory leader Iain Duncan Smith.
All three main parties gave their MPs a free vote on the issue during yesterday’s committee stage of the Human Fertilisation and Embryology Bill.
Labour members will be expected to support the entire bill during its later stages. Lib Dem and Tory MPs are free to vote with their conscience.
Doctors will now consider if women who are candidates for fertility treatment will provide a child with supportive parenting.
Of the 25 members of the Tory frontbench who are MPs, 17 voted in favour of the amendment, including the party leader David Cameron, Liam Fox, William Hague, David Davis, Oliver Letwin and Theresa May.
Shadow Chancellor George Osborne, Shadow Cabinet Office spokesman and former party chairman Francis Maude and Shadow Justice Secretary Nick Herbert voted against the amendment.
Alan Duncan, who along with Mr Herbert is an openly gay Shadow Cabinet member, was absent, as was the Shadow Health Secretary Andrew Lansley and arch-moderniser Michael Gove, the Shadow Secretary of State for Children, Schools and Families. Andrew Mitchell and Peter Ainsworth were also absent.
Prime Minister Gordon Brown was there to vote against the amendment, alongside Cabinet ministers Ed Balls, Hazel Blears, Douglas Alexander, John Denham, Harriet Harman, James Purnell, Nick Brown, Alan Johnson, Jack Straw, Ed Miliband and Jacqui Smith.
Former Deputy Prime Minister John Prescott also voted against the amendment.
Transport Secretary Ruth Kelly, Secretary of State for Culture, Media and Sport Andy Burnham and Secretary of State for Wales Paul Murphy voted for the amendment, but another prominent Roman Catholic, the Secretary of State for Defence and Scotland, Des Browne, voted against.
Former Lib Dem leader Sir Ming Campbell and his successor Nick Clegg both voted against the amendment as did the SNP leader and First Minister of Scotland Alex Salmond.
Prominent Tories who voted for lesbian rights included Ed Vaizey, Eleanor Laing, Nigel Evans and John Bercow.
Leading Labour MPs who voted against included former Home Secretary David Blunkett, Quentin Davies, who defected from the Tories last year, former Sports Minister Kate Hoey, Chris Mullin and Austin Mitchell.
All three SDLP MPs joined the Unionists in voting for the amendment, as did Conservative MP Derek Conway and Labour MPs Ashok Kumar and Lindsay Hoyle.
Former Labour MP and minister Clare Short also supported the amendment, but it was defeated by 292 votes to 217.