For working parents who are already riddled with guilt, it's the last thing you want to hear.
"We find clearly indisputably and unambiguously that the more time children spend in care the more likely they are to be aggressive and disobedient," announced Jay Belsky, who led what is being called the most comprehensive study on the effects of child care to date.
The study followed more than 1,000 kids in 10 cities from birth through kindergarten. The findings, which surprised many of the researchers, reports CBS News Correspondent Cynthia Bowers, appear to fly in the face of other studies that suggest day care has little or no negative impact on kids.
It shows the longer young children spend in day care away from their mothers, the more likely they are to be overly aggressive by the time they reached kindergarten. The study's conclusions are based on ratings of the children by their mothers, those caring for them and kindergarten teachers.
"It's scary considering most of us are going back to work or need some sort of child care," said Lorin Sherman, a new mother.
"There is a constant dose-response relationship between time in care and problem behavior, especially those involving aggression and behavior," said Jay Belsky of Birkbeck College in London, principal researcher for the 10-year federally financed study.
Belsky, a research psychologist who worked at Penn State University until two years ago, added that children who spend more than 30 hours a week in child care "scored higher on items like 'gets in lots of fights,' 'cruelty,' 'explosive behavior,' as well as 'talking too much,' 'argues a lot,' and 'demands a lot of attention.'"
Even more surprising, the results are the same regardless of the type or quality of day care, the sex of the child, or whether the family is rich or poor. What seems to matter most is time. More hours spent away from parents, the more likely the child to have behavioral problems.
But critics are quick to counter that focusing only on childcare is perhaps missing the big picture.
"It's not simply hours away from mother or how stressed and tired parents are. We're finding that about one in four people feel very stressed out and very burned out and it's hard to focus on the kids," said Ellen Galinsky of the Families and Work Institute
In an interview with CBS Radio News, Belsky said researchers couldn't pinpoint how much day care was too much. "What it does imply is that any effort to reduce hours will have a difference," he said.
"From a scientific perspective, we're at a loss to explain the developmental mechanism that's accounting for this," he added, but said he finds it disturbing that more and more children are spending more and more time at yunger and younger ages in day care arrangements away from parents. "Maybe we're just doing too much too soon, and we need to slow down."
"There's nothing about these results that implies that any day care is bad for children," said Belsky in the interview. "What it says is the longer that the longer kids are in day care, the more likely they are to be aggressive."
Sarah Friedman of the National Institute of Child Health and Human Development, which financed the study, said the federal agency "is not willing to get into policy recommendations."
One of the lead scientists on the study with Belsky, she said, "The easy solution is to cut the number of hours but that may have implications for the family that may not be beneficial for the development of the children in terms of economics."
The average time in day care for all those studied was 26 hours per week and researchers found that 17 percent of the children who were in care for more than 30 hours per week were regarded by teachers, mothers and caregivers as being aggressive toward other children. That compared with 6 percent for the group of children in childcare for less than 10 hours a week.
CBS News' Lou Miliano reports that another study presented at same meeting of the Society for Research in Child Development in Minneapolis contends that if you want your toddler to have heightened cognitive and language skills, then day care is the place to be: day care, and more specifically Head Start. New research released Thursday reveals significantly better development of both the toddlers and the parent when the youngster's enrolled.
The two studies prompted one researcher to say the results of day care may be kids who are nasty but smart.
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