Many of them are also juggling childcare with full-time work, while some also care for an older parent, sick partner or friend, a major national study has found.

The research is part of the  Australian Longitudinal Study on Women’s Health, which has surveyed the health of more than 58,000 women since 1996. 

Researchers from the universities of Newcastle and Queensland warn these older women are not being recognised for their child-caring roles and some are at risk of being overburdened.

The researchers report that 60 per cent of women in their mid-60s, and a surprising 12 per cent of women in their late-80s, are providing regular, unpaid childcare. More than half of these are also employed, with 23 per cent working full-time jobs.

“Estimates of economic impact tend to narrowly define informal caregiving as looking after the ill, disabled or frail, and don’t include childcare,” said study director Julie Byles from the University of Newcastle and the Hunter Medical Research Institute.

The report also showed 90 per cent of grandmothers were happy with their share of child-minding duties and were generally in better health than non-carers.

They made fewer GP visits and reported lower levels of anxiety and depression.

However they warned against overburdening grandmothers.

“Roughly one in four women in their sixties are part of the sandwich generation, providing care for a grandchild as well as an adult who is ill, disabled or frail,” she said.

“When these women cared for a grandchild and another adult, they were more likely to be depressed, have higher levels of stress and make more visits to the GP.”

Women’s caregiving roles can occur at multiple points during their lives. They may care for their own children, grandchildren, parents, other family members or friends, and in later decades, spouses or partners.