Parents will be able to share up to a year's leave to look after their newborn children under "radical" reforms set to be announced.
Deputy Prime Minister Nick Clegg said that from 2015 the UK will move to a new system of flexible parental leave as part of a huge shake-up of current arrangements. Under other changes, the right to request flexible working will be extended to all employees to encourage different work patterns for parents.
Mr Clegg is expected to say that "clapped out" rules and working arrangements need to be changed to give women a "real choice" after taking a break from work to have children.
The biggest change covers parental leave, so a mother will be able to trigger leave at any point so that whatever time is left to run on her original year off can be taken by her partner instead.
Parents will be able to "chop up" time together or take time off together, as long as no more than 12 months is taken in total, with no more than nine at guaranteed pay.
Mr Clegg said he had considered extending paternity leave from the current two weeks, but concern had been voiced within Government and from business groups about the cost. Flexible leave will be reviewed by 2018, when extending paternity leave will be looked at, Mr Clegg is expected to announce.
"These are major reforms and, at a time of continuing economic difficulty, it's sensible to do them in a number of steps, rather than one giant leap. More and more men are taking on childcare duties, or want to, and flexible leave builds on that."
Mr Clegg is also expected to say that a new legal right will be given to men to take unpaid leave to attend two antenatal appointments. Added to tax changes, Mr Clegg will say the reforms have the potential to transform opportunities for young parents considering starting a family.
He will say: "That means women up and down the country realising their potential, keeping their independence, fulfilling their dreams. It means children up and down the country benefiting from having their fathers in their lives. It means an economy running on all cylinders, and it means a nation reaping the rewards. Greater equality; a fairer society; a stronger economy too."
TUC general secretary Brendan Barber said: "The reforms will make it easier for parents to choose how they want to share their leave to look after newborn children... These reforms will make life easier for millions of working parents. Businesses will also benefit from a more engaged workforce and a larger pool of people to recruit from."