OTTAWA - New mothers and fathers planning to begin their parental leave on or after Dec. 3 will be able to spread their federal benefits over a longer period of time.

The federal government's long-promised changes to parental leave rules will go into effect early next month, says Families Minister Jean-Yves Duclos, allowing eligible new parents to take up to 18 months of employment insurance benefits after the birth of a child.

On that same date, a new family caregiver benefits will also kick in -- one a 15-week leave to care for a critically ill or injured adult, the other a 35-week benefit to care for a critically ill or injured child.

Eligible soon-to-be-mothers will also be able to claim maternity benefits up to 12 weeks before the baby is due.

However, the government won't increase the actual value of employment insurance benefits for anyone who takes the extended parental leave: instead, the Liberals are sticking with their 2015 election promise to spread 12 months' worth of benefits over 18 months.

The change in rules will automatically give more workers in federally regulated workplaces like banks, transport companies, the public service and telecoms the option of taking time off, and are likely to spur calls for provincial changes to allow the other 92 per cent of Canadian workers access to similar leave.