Tony Blair has been promoting plans to give new mothers an extra three months' paid leave, in a bid to woo families in the run-up to the election.
Three-year-old Elenor Williams joins Mr Blair at the initiative launch
Maternity pay would be extended from six to nine months by 2007 and Labour is consulting about whether paid leave could be transferred to fathers.
But businesses say many small firms could be "crippled" by the proposals.
The Tories dismissed the maternity pay plan as "desperate", while the Liberal Democrats said it was misdirected.
The prime minister told the BBC: "The future is one in which it is incredibly difficult for people to juggle work and family life.
"We need to be extending the ability of people to get help in that situation both in respect of childcare and in respect of extending maternity pay and maternity leave."
The government has pledged to give new mothers the equivalent of an extra £1,400 in extending paid leave.
Trade and Industry Secretary Patricia Hewitt said the cost would be borne by the taxpayer, not employers.
"All of us, whether we have children or not, have a real interest in making sure children are brought up well," she said.
"Children who don't grow up well end up imposing the most enormous cost on the whole of society."Her department is publishing a consultation document, asking for views on whether mothers on maternity leave should have to confirm a return date with employers in advance and transferring part of maternity leave to fathers.
The consultation will also look at extending flexible working rights of parents with children aged six or under to carers or parents of older children.
The proposals were welcomed by the Transport and General Workers' Union who said the government should strengthen rights further.
But the British Chambers of Commerce says its survey suggests 80% of its 100,000 members are opposed to the measures.
And Sylvia Tidy-Harris, who founded the Speaker's Agency, a small business in Leicestershire, said the proposals were designed only to win the Labour party votes.
"It's crazy, it won't work, it's going to make it very difficult for the four million small and medium business owners in this country that make up 50% of the GDP and most of us have five or less employers - we can't do it."
All of the main parties have begun campaigning in the run-up to the general election, widely predicted to be called for 5 May.
The Liberal Democrats have already announced plans for working mothers to get a guaranteed £170 a week in maternity pay for six months after the birth of their first child.
The shadow family secretary, Theresa May, said the Conservatives would announce their proposals closer to the election.
She said: "These plans were announced by Gordon Brown in his pre-budget review in December and Tony Blair is now recycling it in his desperate bid to win back women voters."
New mothers are entitled to 90% of average earnings for the first six weeks after giving birth, followed by £102.80 a week until the baby is six months old.