Women without the shackles of dependent children are more likely to be the main breadwinners in their household, a major study shows.

But women with dependent children continue to do the lioness' share of housework, slaving an average of 15 hours more on housework and 15 hours more on child-rearing than men.

These insights into the home life of Australians come from the Household Income and Labour Dynamics in Australia study (known as HILDA) by the University of Melbourne and edited by Associate Professor Roger Wilkins. It is Australia's only large-scale longitudinal household study.

''It is absolutely true that the decision to have children has big impacts on women's employment and earnings – big negative impacts,'' Professor Wilkins said.

''I would like to think most women know that their labour-market fortunes are going to take a hit from having children, but is the hit bigger than they expected or bigger than it should be? Possibly yes,'' he said.

In households where the woman was the main breadwinner, her children were older and fewer in number. Those women were most likely to be professionals or managers and to be university educated. For men earning less than their partners, the reverse was true.

Men were still likely to work full time,  just on a lower wage.

The most recent data, released on Monday from surveys in 2011, shows that 24.5 per cent of women in household relationships are earning 10 per cent or more than their husbands or partners. It is a marginal increase on 2001 figures.

Men remained the main breadwinners in 69 per cent of households, while women in those households either worked part time or not in paid work.

Professor Wilkins said parents of dependent children appeared to be labouring under the yoke of about 75 hours a week of both paid and unpaid work.

He said for women, this meant 21 hours of housework and 22 hours of caring for children. For men, it meant six hours of housework and 10 hours caring for children. Professor Wilkins said men were most likely to do gardening and ''yard work''.

Overall, women spent 15 hours a week more on both housework and on child-rearing, but the difference was levelled out in paid work, he said.

''You see that difference essentially offset with paid work, with 20 hours for women, and men averaging 46 hours of paid work,'' Professor Wilkins said.

This work figure includes travel times to and from work.

Overall, women are doing less housework, but not all of the slack is being taken up by men. Professor Wilkins said the gap in the amount of work might be done by others outside the household.

''Women have decreased the amount of time spent on housework by slightly more than men have increased it, which suggests either we are living in less clean homes or are eating out more, or we are using more hired help. There are a few possibilities,'' Professor Wilkins said.

''You kind of suspect that in these households where women are working full time or nearly full time, some of them must be using some help – be it babysitting or house cleaning. But, of course, it is also the grandparents who are getting leant on more now than they have been for some decades,'' he said.