The Government is publishing the final details of a significant shake-up which it hopes will, at the same time, cater for a growing desire by men to play a more hands-on role in a baby's first months.
The right to request flexible working patterns will be open to all employees who have done 26 weeks with a firm rather than being restricted to adults' carers and parents of children under 17, or under 18 if their child is disabled.
It means grandparents could apply from April next year for flexible working to help look after grandchildren.
Employers would be placed under a legal duty to consider requests in a "reasonable" manner.
Mr Clegg, who has dismissed the present system as Edwardian, said: "Women deserve the right to pursue their goals and not feel they have to choose between having a successful career or having a baby. They should be supported by their employers, rather than being made to feel less employable or under pressure to take unchallenging jobs.
"Many businesses already recognise how productive and motivated employees are when they're given the opportunity to work flexibly, helping them retain talent and boost their competitive edge."
Under the reforms, rights to the full amount of shared leave will be made available to those bringing up a child born to a surrogate mother and those adopting anyone under 18.
Maternity Action director Rosalind Bragg said the reforms were "a useful but very modest step in the right direction".
But she said the "right to return" arrangements were " complex, unfair and will confuse both parents and their employers" and that more needed to be done to encourage fathers to take up leave.
The CBI, the Federation of Small Businesses and the British Chambers of Commerce (BCC) all said they were pleased that the Government had listened to firms' concerns about being able to plan effectively around parental leave.
John Wastnage, employment adviser at the BCC, said: "T his response appears to offer pragmatic solutions, such as restricting the number of requests or changes to leave to a maximum of three, as this will limit potential disruption for smaller firms.
"The requirements for parents to provide indicative plans for how they intend to use their leave will encourage early dialogue between employers and staff without reducing parents' flexibility."
In sharp contrast, IOD deputy director of policy Alexander Ehmann said the changes would " heap yet more burdens on struggling employers at a time when Government should be freeing them to create jobs and wealth.
"The proposed system is considerably more complex and unwieldy than the current laws and employers will - once again - have to absorb the cost of adapting and implementing this new system," he said.
"Moving the goalposts time and again provides an environment of gross uncertainty that small businesses up and down the country will fear."
TUC general secretary Frances O'Grady welcomed the shared leave but said it was useless without being backed by higher pay.
"The Government's own estimates suggest that just one in 20 dads would be able to afford to take shared parental leave if it was paid at the current statutory rate of just £137 a week," she said.
"By failing to give parents the right to return to the same job after six months, the Government has also missed an opportunity to prevent a constant source of pregnancy discrimination, where mums returning to work find that their job has changed.
"The proposal will create confusion for employers and be a source of anxiety for women who decide to take more than six months of pregnancy leave."
Shadow minister for women and equalities Gloria De Piero said: "Nick Clegg claims to be on parents' side but he and David Cameron have done nothing to support families in the last three years.
"This reheated announcement contains nothing new for families suffering from this Government's cost-of-living crisis. It proves you can't trust a word Nick Clegg says."
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