Grandparents have become a source of child care and also help out with financial assistance.

Grandparents have become an especially important source of child care and also financial assistance. But what they do depends largely on their age, resources and what kind of help their children need, says a study by researchers from the University of Chicago, Clemson University, University of Kansas and Johns Hopkins.

Using data from a National Institute on Aging survey, the researchers found that 60 percent of grandparents provided some care for their grandchildren during a decade — 70 percent of those providing care for at least two years.

The study was published this week in the Journal of Family Issues.

The findings are bolstered by research just out from MetLife Mature Market Institute and the nonprofit Generations United, which found nearly 60 percent of grandparents have at least one grandchild within 50 miles, 62 percent have provided financial support and nearly three-fourths at least baby-sit weekly.

"Over the years, the lives of grandparents have changed due to longer lifespans, health advantages, evolving lifestyles, a more mobile society and changing views of retirement. But while the roles of grandparents have evolved, they continue to have a steady and important position in the lives of their children and grandchildren," the MetLife research said.

An earlier survey by the U.S. Census Bureau had found that 8 percent of grandparents live in the same households with grandchildren and 2.7 million grandparents are primary caregivers, not just helpers. Grandparents are also the main child care provider for 30 percent of working mothers who have children under age 5, the background information for the Chicago study said.

"Our findings show that different groups of grandparents are likely to provide different types of care. Importantly, grandparents with less income and less education, or who are from minority groups, are more likely to take on care for their grandchildren," Linda Waite, sociology professor and co-director of the Center on Aging at the University of Chicago, said in a written statement explaining that study. She was one of the study authors.

For the study, which was conducted between 1998 and 2008, 13,614 grandparents 50 and older were interviewed every two years to determine how much care they provided. Most grandparents provide some care. It was based on a longitudinal survey that the University of Michigan has been doing every other year since 1992.

"We took people who didn't live with their grandchildren and looked at how many hours of care they provide," Waite told USA Today. For some people that might mean "baby-sitting for going out. For sure, it's day care for some people."

She added that the 39 percent who didn't baby-sit at an intense level were often still very involved, but their grandchildren could have been older and not required that kind of care, grandparents could have been in poor health or unable to provide care and in some cases they lived too far apart for direct care.

Both multi-generational households and skipped-generation households, in which grandparents care for the child in lieu of absent parents, were part of the first study.

They found Hispanic grandparents are more likely to start a multi-generational household, while grandparents with more money and educations were most likely to baby-sit. Whites were less likely than either Hispanic or African-American grandparents to live in multi-generation or skipped-generation households.

Grandparents are less likely to provide care if they have minor children of their own at home. And grandpas are less likely to provide care to grandkids, unless grandma is around. But married grandparents are more likely to baby-sit.

The grandparents least likely to provide care are "older, unmarried and less likely to be working," the researchers said.

The MetLife survey reported that one in five grandparents live in multi-generational households, with 30 percent of those sharing a household with grandchildren.

The grandparents said the traits they most hope to pass on to their children and grandchildren are honesty (88 percent), good behavior (82 percent), self-sufficiency (70 percent), higher education (69 percent) and good health habits (68 percent).

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