Poor promotion opportunities for mothers returning to the workforce are another factor behind Australia's diminished birth rate, says an expert.
An Australian Public Service Commission survey found two out of every three women who took maternity leave from the public service did not receive promotions after their return to work.
Stephen Jones, national secretary of the Community and Public Sector Union, said that when women took leave to have a baby, their re-entry into the workforce was "often less than perfect".
"It's all about choice. If a woman, or a father for that matter, makes a choice to take a backward step in their career (for a child), then that's a matter of choice," he said.
"But when it's not their choice, when the prejudice in the workplace makes that choice for them, it's a completely different matter."
The study looked at the progression of female public servants who took maternity leave in 2000-01 and found that 65 per cent of them had not been promoted as of June last year.
In the same period, 42 per cent of women without children had not received a promotion in the same period.
Mr Jones said the fall in opportunities came down to a range of factors, including a lack of flexible working arrangements, a bias against providing part-time work opportunities in higher grades, and a lack of well-funded and quality childcare arrangements.
Mr Jones believes these challenges have impacted Australia's birth rate, which has been steadily declining since the early sixties.
"Everyone acknowledges that there's been a decline in birth rate," he said.
"That sort of long-term issue isn't going to be addressed if we're placing rigidities and barriers in place to people who want to have a career and family."
More than a dozen prominent Australian organisations today said they would put their names to a push for six to 12 months' paid maternity leave, which may lower one barrier for working women who want families.
New research by Unions NSW found Australia failed to make it into the top 20 countries in terms of paid maternity leave provisions.
"A six- to 12-month paid maternity leave scheme is not a radical proposition when you consider Sweden, the UK, Denmark and Canada are already at this level or above, and we believe this should be the starting point for discussion," Unions NSW secretary John Robertson said.
He said health professionals, early childhood development experts, women's groups, unions and the Independent Commission for Children and Young People agreed mothers and babies needed at least six months together.
Mr Jones said the public service, which has some of the most competitive family-friendly work provisions in Australia, including 12 weeks' paid maternity leave and flexible working hours, should be setting an example.
"If the largest employer in the country can't have flexible work arrangements that enable people to balance careers and families, then there's no hope anywhere," he said.
"In my view the public sector is in many instances ahead of the private sector, so if you did the same sort of analysis in the private sector, you'd find even greater disparities."
Mr Jones said it was in the interests of the employer to take stock of the study and not risk losing valuable staff in what is already a very tight and competitive labour market.
