Australia and the United States have tied as the worst of 21 high-income nations in terms of generous paid parental leave.

Researchers at the US-based Centre for Economic and Policy Research examined the parental leave policies of 21 countries with their study published in the peer-reviewed social science Journal of European Social Policy.

They found Sweden ranked highest for gender equality in parental leave practices, while Germany and Sweden were the most generous with paid parental leave, both offering 47 weeks.

Last month Australia passed its first paid parental leave legislation that ensured 18 weeks paid leave at the minimum wage for mothers starting next year.

US researcher Janet Gornick says the US and Australia rank as having the least generous parental leave policies.

"We pay a high price for meagre policy, because parental leave improves the health and well-being of children and their parents and paid leaves provide families with crucial economic support at such an important time," she said.

The study looked at parental leave policies according to three criteria: total time guaranteed for parental leave, whether leave is paid or unpaid, total paid leave and gender equality of the parental leave such as leave and pay available to fathers.

Ms Gornick says while all 21 countries protected at least one parent's job for a period, there were great differences across these countries on each of the three criteria.

France and Spain came highest in terms of total guaranteed leave, each giving over 300 weeks, while Australia and the United States ranked at the bottom with 18 and 14 weeks respectively.

Australia and Switzerland ranked near the bottom in terms of both generosity and gender equality of parental leave.

- Reuters