It was, as one NPR commentator put it, the kind of research finding that "drives working moms berserk." Last summer, respected researchers at Columbia University published a study in the journal Child Development linking the scores of three-year-olds on measures of cognitive and verbal development to whether their mothers had worked full-time during the children's first nine months of life. A New York Times headline announced the key finding: "Study Links Working Mothers to Slower Learning." Syndicated columnist Ellen Goodman confessed that it "registered a full 'eek' on the guilt meter." Business Week columnist Toddi Gutner guessed that she was joining many other working mothers in "assessing the damage they had inflicted on their children."

Of course, the conclusion about the effect of mothers' full-time employment emerged from a complicated analysis, and the researchers took pains to urge parents not to jump to simplistic conclusions or second-guess decisions they have made. But research results that coincide so exactly with parental anxieties have a way of sticking in the brain. As the father of twin girls who spent a good part of their first year in day care, I found my own initial impression of the headline lingering, uncomfortably.