November 3 (HealthDay News) -- When grandparents act as caregivers for children of working parents, the risk of childhood injury is reduced by about half, says a U.S. study that challenges the widespread belief that children are more likely to suffer an injury while being cared for by grandparents.

Compared to organized day care or care by the mother or other relatives, having a grandmother take care of the children was associated with a decreased risk of injury, said Johns Hopkins Bloomberg School of Public Health researchers.

"Recent growth in the number of grandparents providing child care has some observers concerned they don't adhere to modern safety practices. To the contrary, this research tells us not only is there no evidence to support this assumption, but families that choose grandparents to care for their children experience fewer child injuries," study author Dr. David Bishai, a professor in Bloomberg's department of population, family and reproductive health, said in a news release.

"As injuries are the number one cause of death for children in the United States, it's critical we continue to determine risk and protective factors," study co-author Andrea C. Gielen, director of the Center for Injury Research and Policy in Bloomberg's department of health policy and management, added.

"Additional studies of how households choose relatives to watch their children and the actual caregiving style of grandparents are warranted, because the protective effect of grandparents may depend on choosing the right grandparent," Gielen said.

For this study, the researchers analyzed data from the National Evaluation of the Healthy Steps for Young Children Program, which includes more than 5,500 newborns enrolled in 15 U.S. cities, with follow-up for 30 to 33 months.

In addition to caregiving, the researchers studied the association between family structure and injury risk. The likelihood of injury was higher among children whose parents never married than among children whose mothers stayed married throughout the child's life. Children in homes in which the father didn't reside were also more likely to suffer injuries. These associations were independent of family income.

The study was published in the November issue of Pediatrics.

SOURCE: Johns Hopkins University Bloomberg School of Public Health, news release, Nov. 3, 2008