> Just 5.6 percent of female baby boomers were employed full-time year-round when their children were 5 years old younger. A full 38.1 percent of Generation X mothers do so.

> One-third of female baby boomers worked while they had young children. More than three-quarters of Gen Xers do so.

Also, more female professionals are working longer hours. Ten percent of Gen X moms with young children work more than 50 hours a week, while only 1 percent of baby boomers with young children did so.

It's not decreased fertility that's leading more women to enter the work force, either. The fertility rate has remained similar for women born 1949 to 1975.

Percheski says more working women probably doesn't translate into less work at home. "We can't assume that combining professional work and family life is easy for most women," she says. "Many working women successfully combine these roles by making great personal sacrifices, including curtailing their sleep, civic involvement, and leisure time."

The research is featured in the June issue of the American Sociological Review.