As for the downside of day care: several studies, including those using the NICHD’s data, have found that the more time kids spend in day care (and especially center-based care rather than, say, family day care), the more behavioral problems they develop later as reported by teachers. These effects include being more disobedient through age 4½ (and through the sixth grade for kids from center-based care); having poorer academic habits and social skills in the third grade; and being more impulsive and taking more risks at age 15. Again, the experts I talked to couldn't give specifics on how big these effects were, but one reassured me that the behavior of day care kids is still usually well within the normal range. Many—but not all—of the studies suggest that these problems develop even after high quality care, so quantity really seems to be the crux of the problem, yet there doesn't seem to be a threshold where these effects start, either—it's not that 20 hours a week doesn't cause any problems but 22 does. Some studies do, however, suggest that certain kids—those, for instance, with “difficult” temperaments—are more sensitive to quality than others, in that they are more likely than other kids to develop behavioral problems from low-quality care and can even glean social benefits from high-quality care.
It’s important to keep in mind some of the (major) limitations of these studies. They were designed to find associations, not cause-and-effect relationships. Parents who use day care differ in many ways from parents who don’t. Yes, there are stay-at-home moms found in all income brackets, and both poor and affluent families put kids in day care. Still, on average, parents who use day care tend to have higher incomes and fewer kids than those who don’t. They are “much more advantaged in almost every way,” says Margaret Burchinal, a senior scientist in the Frank Porter Graham Child Development Institute at the University of North Carolina at Chapel Hill, who was also involved in the NICHD study. Affluent families tend to enroll their kids in higher quality day care, too (although don’t assume your day care is awesome just because you’re paying a fortune for it: The majority of day care in this country is mediocre).
This means that studies on the effects of child care compare different types of families to one another, not just differences in child care use—and as I mentioned before, the former is a much more significant influence on kids than the latter. Although studies try to control for the impact of education and income and the like, this so-called selection bias “is a huge factor,” Burchinal says, and it’s unclear, exactly, how these confounders might impact results. On the one hand, one could imagine that the better home life of advantaged kids might mask or compensate for the negative effects of day care, but on the other hand, the benefits of group care may be smaller for these kids, too (for more on this idea, read my preschool column). Interestingly, when researchers compared how well children fared if their mothers did or did not go back to work before their first birthday and then broke results down by race, they found that full-time work in the first year by white, non-Hispanic mothers was associated with poorer cognitive development in their kids through the first grade, but that full-time work by African-American mothers was not. It’s unclear exactly why.
It’s easy to imagine why day care might boost language scores—I know my kid interacts with lots of people all day long. But the causes of the negative effects are still a head scratcher. Day care doesn’t, for instance, seem to disrupt the mother-child attachment bond. One possible answer Belsky provides is group size: The NICHD data suggest that the more kids a child spends time with in day care, the more unruly he becomes, but the evidence on this isn’t clear-cut, either. Huston notes the types of kids in a child’s group might make a difference—if your kid is spending time with a bunch of brats, he might turn into a brat too. Other work suggests that America's heavy use of early day care (we're one of the few countries with parental leave policies requiring kids to be put into care as young infants) could be a problem, since good baby and toddler care requires a high ratio of staff to kids and centers aren't always willing to pay for that. Or, others say, maybe there's just something about the cultural climate in the U.S. that makes day care more harmful here, because studies have shown that day care in Norway, which has much more supportive family policies (and better day care), causes few, if any, social problems. One of Belsky’s concerns, which is backed by a study, is that the negative effects of day care here in the U.S. might compound in grade school, in that classrooms comprised mostly of kids from day care might be poorer learning environments than classrooms made up mostly of kids who stayed at home, because all the little behavioral effects will add up and teachers will end up spending their time trying to control their students rather than, you know, teaching.
So what’s a parent to take from all this—particularly one whose child is in day care all the time? My first instinct was to cry; my second was to attach a camera to my son’s shirt to see what his days were really like; my third was to get really, really pissed at our government for not doing more to ensure that U.S. child care is higher quality. (U.S. child care workers earn less than janitors and amusement park attendants. Outrageous, right?) But there’s another aspect to this body of research that I haven’t mentioned yet, and it’s reassuring, at least to me. In addition to collecting data on child care use and income and the like, researchers with the NICHD also asked mothers—both those who used day care and those who did not—questions about how they felt about day care. Should a mom stay home with their kids, they asked, or should she feel comfortable using group care and going back to work? When moms said it was better for mothers to stay home with their kids, and these mothers did stay home with their kids, their children fared very well. When moms felt that it is OK to work and put kids in child care, and these moms did work and put their kids in child care, their kids did great too. In other words, “when the mother’s choice was congruent with what she wanted and believed, children did well,” Burchinal says. What’s best for you, then, may well be what’s best for your kids, too.
In addition to the sources mentioned, The Kids would also like to thank Jane Waldfogel at Columbia University and Katherine Magnuson at the University of Wisconsin at Madison.