The working women of Sydney will be among the hardest hit in Australia if the Abbott government pushes ahead with its plan to crack down on so-called paid parental leave "double dippers".

A new analysis shows close to 40 per cent of working women aged 20 to 44 who live in the federal electorate of Sydney – held by Labor's Tanya Plibersek – could potentially lose under the plan to stop women accessing both employer and taxpayer PPL schemes.

That's the third highest proportion of all 150 lower house seats.

Six other Sydney seats – Grayndler, Wentworth, Parramatta, Kingsford Smith, North Sydney and Greenway – feature among the top 20 hardest hit. Of the seven, five are held by Labor and two by the government.

The analysis initiated by the Australian Greens – which combines census data with Productivity Commission figures on the proportion of women estimated to be eligible for employer PPL in each industry – suggests the majority of electorates that will be hit hardest are not held by the government.

Of the top 20, only five are held by the coalition. Fourteen are held by Labor and one by Greens MP Adam Bandt.

Ms Plibersek says young families considering having a baby need a government that supports them, not one that accuses them of fraud.

"I know that young families in Sydney, where cost of living pressures are already high, will really struggle," she said.

Mr Bandt, who represents the potentially hardest hit seat of Melbourne, says Prime Minister Tony Abbott feigned feminism to get elected but now his "brutal chauvinism" is shining through.

Mr Abbott is facing a fierce backlash to the plan, which aims to save the budget $1 billion. Tony Abbott has faced particular criticism given he wanted to set up a much-more expensive taxpayer-funded PPL before his party room forced him to dump it.

The government's case was further undermined when it was revealed the wives of Finance Minister Mathias Cormann and Assistant Treasurer Josh Frydenberg had both "double dipped" when they had children.

The government estimates almost 80,000 women will lose out under the plan every year. About 34,000 will lose all access to the taxpayer scheme, while about 45,000 will get only a partial payment.

While the analysis is based on the most recent, 2011, census data and a 2009 Productivity Commission report – it doesn't take a woman's income into account – but offers a reliable estimate on where the cuts will hurt most.

But a spokesman for Social Services Minister Scott Morrison said the analysis was "contrived and confected".

"The government remains committed to ensuring we have a PPL scheme that is fair to everyone, especially those working for small businesses who don't receive generous public sector PPL entitlements," he said.

Labor and the Greens have vowed to fight the government's plan in the Senate. The crossbench is split on the proposal, meaning the cuts may be blocked

Prime Minister Tony Abbott said Labor wants increased spending on childcare but won't support the cuts to make it possible.

"It never adds up with the Labor Party, it's magic pudding economics."

Under the government's plan, women who can access employer-sponsored PPL schemes will lose all or part of their taxpayer-funded PPL, which pays the minimum wage of $641 a week for up to 18 weeks.

Opposition Leader Bill Shorten has accused the coalition of "lies and hypocrisy" after it emerged the government's own Fair Work Ombudsman recommends in its best practice guide a mix of employer and taxpayer PPL.