Moms’ Hours May Affect Development

Having mothers who work evenings, nights or other nonstandard schedules appears to dampen the intellectual development of young children, according to a study published today in the journal Child Development.

The primary reason, said study author Wen-Jui Han, is that such children are less likely to be enrolled in the stimulating environment of day-care centers. Instead, their mothers tend to rely on a patchwork network of family, friends and others for their child-care needs.

“The type of child care is the most important factor,” said Han, a professor at the Columbia University School of Social Work. “Studies show that if kids attend center care by the age of 3, they do have much better cognitive performance.”

Other factors may also be at work, she said. For instance, mothers who work at night may be too tired to provide a stimulating environment for their children during the day. Mothers who work irregular schedules are also more likely to have lower income and education levels.

But the quality of child care trumped all other variables, said Han, whose own 20-month-old daughter is in day care.

Han examined data on 900 children who were tracked by the National Institute of Child Health and Human Development’s study of early child care for at least the first 36 months of their lives.

The children’s cognitive development was measured by testing the development of their vocabulary and other language skills. In general, kids whose moms had unusual work schedules performed worse on the tests.

The number of women working nonstandard hours is rising, according to previous studies. In 1980, about 16% of women who worked full time had irregular schedules; by 1997, that figure had jumped to 33%.

Women’s schedules are not changing much once they become mothers. One-third of dual-earner families with children have at least one parent who works evenings, nights or rotating shifts, said Harriet B. Presser, a professor of sociology at the University of Maryland.

As a result, “millions of couples are juggling child care,” said Presser, author of “Working in a 24/7 Economy: Challenges for American Families.”

“The more caregivers, the more likely child care is to break down,” she said. “Unstable child care, whether in the day or at night, is not good for children.”