The Conservatives were wrong to suggest that a woman's place was in the home, said shadow chancellor George Osborne.
Women who work should not feel guilty, says Osborne
He also criticised the impression given by Labour that "all young mothers should work - both are wrong".
"We need a new approach... instead of imposing a choice on mothers we should support the choice that mothers make," he said in a speech in London.
He was speaking as new Conservative leader David Cameron returned to work following his son Arthur's birth.
In his speech, "Women at Work and Childcare", Mr Osborne said the Tories were determined to put "support for families and their childcare choices at the heart" of party policy at the next election.
It came as the Women and Work Commission found that women in full-time work were earning 17% less than men.
Mr Osborne argued that unequal pay based on sexual discrimination was "totally unacceptable in this day and age".
And he added that issues, such as childcare had been seen "for too long" as "peripheral to the mainstream political debate".
"Let's be honest - in the past the Conservatives have given the impression that young mothers should stay at home," he said.
'Drop the guilt'
"Today the Labour Party gives the impression that all young mothers should work - both are wrong.
"Both are trying to impose choices on mothers.
"We need a new approach for a new generation. Instead of imposing a choice on mothers - we should support the choice that mothers make for themselves."
He said mothers who work "should not be made to feel guilty", but neither should mothers "who stay at home".
"Let us stop trying to tell families how to live their lives - let us instead support the lives that families live."
Mr Osborne said the Tories supported the government's SureStart scheme, which provides support for the parents of young children.
But he was critical of Mr Brown's argument that "when it comes to balancing work and family life, only the state can guarantee fairness".
"His eyes lit up when he called the provision of childcare for children up to 48 months 'a whole new frontier of the welfare state'," said Mr Osborne.
"At its worst it is a vision of a Brave New World: rows of mothers at work and rows of tiny children in uniform state-run nurseries - a real nanny state.
"Instead, I believe that every family wants something different from childcare.
"Each has different needs, different desires and different decisions to take. You cannot impose a one-size-fits-all model of childcare provision."
Mr Osborne said the Tories will be guided by the need to provide financial support for families who use childcare and increasing the choice of childcare available to parents.
He said the party also wanted to protect women who "want to be good mothers and have good careers".
"These are the principles that will guide our thinking in the months and years ahead."