Fathers in low-income families are less likely to take paternity leave
Statutory maternity leave should be cut from nine months to six to give fathers more paid time off to spend with their children, a watchdog has said.
The Equality and Human Rights Commission said it wanted to see more sharing of paid leave between parents.
Mothers get nine months' paid leave while fathers get two weeks, making arrangements in the UK the most unequal in Europe, the commission suggests.
The government said the UK already had generous measures to support parents.
New mothers currently get nine months paid leave, six weeks at 90% of their salary and the rest at the statutory rate of £117.18 a week. Fathers get two weeks at the statutory rate.
The commission's survey of 4,500 people found "a high percentage" of fathers said they wanted to spend more time with their children.
The commission suggested new fathers should get two weeks off at 90% pay, and another four months leave before their child was five years old.
Mothers are entitled to 52 weeks' maternity leave, with 39 weeks on full or partial pay.
Deputy chairwoman, Baroness Margaret Prosser, said many women could not afford to take the full leave available to them because much of it was unpaid.
"We're saying let's add those weeks together, let's allow parents to choose, to share those between them," she told the BBC.
"Let's ensure that more of those weeks are paid at what we would suggest - 90% of a person's income - and then we're likely to get both parents taking that leave in a way that's more suitable to them."
The commission published a 10-year strategy calling for higher levels of maternity and paternity pay to increase uptake, particularly among men, lone parents and lower-income groups.
Fathers in families with an income of less than £15,000 were less likely to take paternity leave, it said.
The new plan would cost around £5.3bn to introduce.
Nicola Brewer, the commission's chief executive, said: "When it comes to modern approaches to parental leave, we may need to try a different route.
"We are proposing one of the most radical changes in our approach to parental leave in a decade.
"Changing the way we approach parental leave could be one way of tackling the gender pay gap.
"By supporting men to be good fathers as well as good employees, it would also help children to do better at school."
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The Department for Business said it recognised the importance of ensuring mothers and fathers were both able to spend the time they needed with their families.
It added that the UK already had generous and progressive measures to support parents.
"The UK has made great progress on providing support to working parents over the last decade," a spokesman said.
"All women are now entitled to 52 weeks' maternity leave, with 39 weeks' pay - increased from 18 weeks' pay in 1997.
"The rate of maternity pay has more than doubled from £55.70 in 1997 to £123.06 from April this year."