But being the primary caregiver does not necessarily harm grandparents' health, according to a new study by a University of Chicago sociologist.

Previous studies have indicated that raising grandkids can take a toll on grandparents' health. But the new study by U. of C. professor Linda Waite indicated otherwise.

"What we found is that there is virtually no evidence that taking care of your grandchildren had any bad effects on people's health," Waite said. "What we did find is that the people who live with their grandchildren and are in poor health were in poor health to begin with."

Grandmother Jan Merrick, who is raising her daughter's kids, said there is additional stress with raising grandchildren, but she would agree with Waite's findings, which are based on a 15-year study of 13,000 grandparents.

"I was a lot sicker because I was older, but I don't think my health would have been any different," Merrick said. "I had things wrong with me as I got older, but that was because of age."