Think of it as a new ''normal'' in American family life.

After creeping slowly and steadily upward most of the last 50 years, the number of babies born to young unmarried women quietly crossed a troubling threshold in 2006.

For the first time in a half-century of record-keeping, a majority of babies born to women younger than 30 were delivered by single women.

That year, women such as Sara Bell of Lexington, Mo., delivered 50.4 percent of the children born to those under 30, according to Andrew Sum, an economist at Northeastern University in Boston.

The nation got a reminder that unwed pregnancies can happen anywhere when Republican vice presidential candidate Sarah Palin announced that her 17-year-old daughter, Bristol, was five months pregnant. The family said Bristol will keep the baby and marry the baby's father.

Bell, now 24 and newly married, bore her first child when she was 19 and single. That baby died a day later, and Bell went on to give birth to two more children, with different fathers.

As a college student, she was burdened with homework as well as the draining work of caring for two children. She remembers the thought that danced through her mind during moments of exhaustion.

'There were times when I was like, `This is why people marry when they have a kid.' ''

Bell had a great deal of help from her mother and relatives. In June, she tied the knot, shifting her single-mother status to married with children, solidly middle class with two paychecks.

For the vast majority of single young mothers, however, that's not the story. In fact, Sum, who directs Northeastern's Center for Labor Market Studies, warns that the burgeoning number of such families presages ''disaster.'' His 2006 calculations are his most recent.

''The inequality of incomes in these families is unbelievable,'' said Sum, who has written numerous books and articles about the job market, young families and poverty. ``Forty percent are poor, or near-poor. A large fraction is dependent on public assistance. Unless the mother is very well-educated and has a bachelor's degree or above, there's a huge fiscal cost to the rest of us.''

Most of the mothers are not college-educated. In fact, the story of the American family has split into two widely divergent realities, according to Sara McLanahan, a professor of sociology and public affairs at Princeton University. By and large, she said, college-educated women are marrying later, having babies within a marriage and divorcing less. Their husbands are spending more time with the children.

Women without a college degree are doing just the opposite -- and in growing numbers.

''The next generation of children is going to be much more unequal than what we have today,'' Sum warned. 'You're going to have a really elite group and a group that will massively fall behind. These gaps are really extraordinary. I testified before Congress and said, `Look, guys, we really need to face this.' ``

Sum advocates providing more public assistance and tax breaks for low-income families, especially those in which the parents are married and working.

Private family miseries translate into major public burdens, he said.

''You can't raise revenue from families that have such a low income,'' Sum said. ``And you have to spend so much more to keep them afloat.''

He estimates that taxpayers pony up about $7,000 a year to support the typical family of an unwed mother without a high-school diploma.

Join the discussion

Note: If this is your first time using our NEW commenting system, you will have to LOG OUT and then LOG BACK IN.

The Miami Herald is pleased to provide this opportunity to share information, experiences and observations about what's in the news. Some of the comments may be reprinted elsewhere in the site or in the newspaper. We encourage lively, open debate on the issues of the day, and ask that you refrain from profanity, hate speech, personal comments and remarks that are off point. In order to post comments, you must be a registered user of MiamiHerald.com. Your username will show along with the comments you post. Thank you for taking the time to offer your thoughts.

     Showing: Oldest first Newest first Most-recommended first Least-recommended first

@Nyx.AuthorDisplayName@ wrote on @Nyx.PostedAtTime@:

@Nyx.CommentBody@

@Nyx.Recommender@ @Nyx.AbuseReporter@