an historic measurement first: women having babies at an earlier age

From Sue Shellenbarger in the WSJ...

For the first time since government records have been kept, the average age at which women have their first babies posted a decline -- according to newly released data from the National Center for Health Statistics. Mothers' mean age at their first childbirth fell to 25.0 years in 2006, the most recent figures available, from 25.2 in 2005. Women ages 20 to 24 led the shift, with a 5% increase in the rate of first births.

A one-year reversal doesn't make a trend, of course. But the study lends weight to anecdotal evidence that young women are tuning in more closely to their biological clocks. "It's the first time it's ever gone down, and certainly that's noteworthy," says Brady Hamilton, co-author of the study.

Other factors are at work too, including rising numbers of Hispanics, who tend to start families sooner, says Steven Martin, an assistant professor of sociology at the University of Maryland. A 4% rise in the rate of first births to older teens, ages 15 to 19, is also playing a role. And the sheer size of the baby boomlet generation, now entering the child-bearing years, may be skewing new mothers' mean age lower.

But some experts also see a shift in attitudes. More young women today just assume they'll have both a career and a family, and on their own timetable, says Stephanie Coontz, director of research for the Council on Contemporary Families. Young women feel less compelled to spend a decade proving themselves on the job before kids, she says....

It's unclear whether the country's current economic woes will affect the move toward younger child-bearing. Historically, recessions have reduced family size, but their impact on the age at which women start families is less clear....