Grandparents who care for children could be allowed to share unpaid parental leave if Labour wins power.
Labour has pledged a consultation on allowing new mothers and fathers to transfer part of their flexible parental leave to grandparents.
In its women's manifesto, launched on Wednesday, the party warns that too many grandparents feel pressured to give up their jobs to help with childcare duties so the baby's parents can return to work.
The radical move would allow grandparents to take time off "without fear of losing their job". Under laws introduced by the coalition, couples can already share up to 50 weeks of parental leave between them. But Labour's proposal would allow grandparents to get involved too.
Shadow home secretary Yvette Cooper told BuzzFeed News: "Lots of working parents wouldn't cope without grandparents. For us, my mum is like the fourth emergency service – the person we call when we suddenly have a crisis and need someone to look after the kids. More and more working-age grandparents want to be able to help out.
"But right now that's hard. Parental leave helps mums and dads manage as their children get older if they are off school sick, or have doctors' appointments, or to cope with a childcare crisis. But why shouldn't they be able to share that leave with grandparents too – so every generation can stay involved in supporting family life? A Labour government will consult on sharing parental leave with grandparents."
Labour's deputy leader, Harriet Harman, first revealed in 2013 that she was pushing for so-called granny leave to be included in the party's manifesto. But she clearly faced some opposition because Labour is only promising a consultation on the matter.
Labour also pledged to double paid paternity leave, introduce compulsory sex and relationship education, and step up action to stop violence against women and girls.
Cooper said the Tories had "turned the clock back for women across the country". She said: "I think David Cameron has got a real women problem, I think he has a real blind spot when it comes to women's lives, I don't think he gets it and understands at all. And that's why women have been so much harder hit."
She also defended Labour's pink bus, which is being used to try and win over women voters. "In the 2010 election we had a women campaign bus – and it was white and nobody noticed it," she said. "The media didn't pay any attention to it, it didn't get the campaign rolling, I went on it several times and we did school-gate campaigning and door-knocking and so on and nobody noticed it.
"I think there was rightly a general view that women disappeared from the 2010 campaign, and we needed to make sure that women's lives were central to this election campaign."