Working mums need not worry that they are harming their children, study finds.

For most mothers, the days of staying at home until the youngest child starts school are over. And for this we can thank the Howard government's childcare rebate, introduced in 2006.

By 2008, more than half of mothers with partners - 52 per cent - were returning to work before their youngest child turned two, according to new labour force figures from the Melbourne Institute of Applied Economic and Social Research.

This indicates a big jump in mothers returning quickly to their jobs since the institute started collecting figures in 2001 for its Household, Income and Labour Dynamics in Australia Survey (known as HILDA) , a survey of 7000 households. In 2001, just over two in five mothers with partners - 40.3 per cent - were back at work before their children's second birthday.

As the rebate reduced fees by 30 per cent in 2006, and then by 50 per cent in 2008, the numbers of mothers in the workforce increased also, said HILDA researcher Diana Warren. This is confirmed by the steady rise in the number of women in the workforce since 2006 - from 4.5 million to 5.19 million - and the rise in the number of children in formal childcare.

In the June quarter last year, 869,770 children were enrolled in formal childcare, up 8.7 per cent from June 2009. The numbers are tipped to rise again next financial year, as families can get the rebate deducted directly from their fortnightly bills from July 1.

D'arne Buckley returned to her job part time when her daughter turned one. ''I work in advertising,'' she said. ''If I had more time off, it would be really hard to get back in the industry.'' Like 72 per cent of couples surveyed, the greatest challenge for Ms Buckley and her husband was finding daycare.

For union organiser and single mother Melissa Wainwright, the rebate is a godsend. ''My rebate's more than 60 per cent now,'' she said. Like many women, the reason she has been able to work full time since her son was eight months old is that her employer gives her flexible hours: she finishes at 4pm most days, and took a small pay cut in return for an extra two weeks' leave.

Nicole Maher, a single mother who works for the Environmental Protection Agency, said flexible working conditions allowed her to pursue her career, study law and care for her four-year-old daughter. ''I want to make it work, so I do make it work,'' she said. ''The stress comes from making the decisions. Is it worth the money? Trying to work it out all the time is stressful.''

Single mums who work full time reported the highest levels of stress, which may account for the drop in single mothers returning to work in 2008 before their youngest child turned two - from 40 per cent to 28 per cent.

Single mums reported twice the difficulty of partnered mothers in finding childcare to suit their hours and managing their children's sick days, suggesting that workplace flexibility remains a challenge for those who may need it the most.

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