But moms shouldn't panic, says Jane Waldfogel, Ph.D., one of the authors of the study. "This is an average effect -- it doesn't mean that your child will be negatively influenced," she says. The study also doesn't prove that the lower test scores are necessarily due to working -- perhaps there were other, preexisting differences between mothers who did and those who did not work full-time.
It's a good idea to evaluate all the factors that matter to your child's development, says Ellen Galinsky, president of the Families and Work Institute, in New York City. The researchers found that a stable home environment, high quality of childcare, and sensitive maternal care bolstered the children's test scores. And keep in mind that previous studies have shown that whether a child's mother works has no effect on cognitive development or academic performance in the long term.
One clear conclusion: The burden of juggling both a job and a family shouldn't rest solely on working parents' shoulders. "As a society," says Waldfogel, "we need to offer moms and dads more choices -- better childcare, longer parental leaves, and the opportunity to work part-time or flexible hours."