When researchers from Johns Hopkins University tested an impoverished 8-year-old Baltimore girl, they weren't surprised to learn that her reading skills lagged several years behind those of her classmates.

What the researchers were surprised to learn is that the age of her mother at the time the girl was born might be just as accurate as her family's income level in predicting the girl's prospects for success."Her grandmother was a teen mom, her mother was a teen mom," said Janet Hardy of Johns Hopkins School of Medicine. "She's already got several strikes against her.

"The chances are that she will be (a teen mom also) but we can't be sure. We know she's in a risky situation."

The girl's mother was 17 when she had her first child. The 8-year-old represents the third generation of welfare recipients in her family. Conventional wisdom says the latter fact will affect the girl's future education, income and health more than the former.

But in a study that spanned several decades, Hardy - along with other scholars from Johns Hopkins and Columbia University as well as Brigham Young University statistics professor Sterling C. Hilton - concluded that children whose mothers are under 20 years old at the time they are born have less favorable adult outcomes than those whose mothers are 20 or older, regardless of factors like mothers' education, income and marital status.

Children whose mothers are 25 or older have the best outcomes of all, according to the study, which was published in the journal Pediatrics last November.

"I think this has implications for public policy," Hardy said. "We really ought to let people know that having children while young compromises their (the childrens') chances."

Hardy suggested that older mothers might be more mature and have more resources than younger moms, thereby affording their children a better chance at succeeding. The study defined success of the children as achieving a high school diploma, being independent of welfare assistance and delaying birth of their own children until at least 20.

In the 1960s, Hardy engaged in research along with scholars from 10 other medical centers. The object was to track 50,000 pregnancies to determine if things that happened to the mother while pregnant were related to abnormalities in the children.

While moving her office in 1990, Hardy encountered the 60 five-drawer file cabinets full of data from the study. She had conserved the records of 2,694 children born in Baltimore between 1960 and 1965.

She gathered a team of experts to decide how they could use the data for further research. Because there seemed to be a growing interest in the adult outcomes of children from various socioeconomic backgrounds, the researchers decided to try to contact as many of the children in the original study as possible and see how they had fared.

During the next few years, the scholars located 71 percent of the children, most of whom were in their early 30s. One of them was playing in the National Basketball Association. Another had played football in college and then started his own business, earning more than $200,000 per year. Others were in jail or homeless.

One of them - the mother of the 8-year-old girl with reading problems - was living in a public housing project in Baltimore.

"One of the things that's fascinating for me is the diversity of outcomes," Hilton said. "Here you've got individuals who start out in the same place - many of them indigent - and they end up doing so many different things."

But the one thing that cut across racial and gender boundaries was that those whose mothers were teenagers at the time the child was born had a lesser probability of getting adequate education, holding down a good-paying job and delaying parenthood.

"These findings indicate that in this population of children born to inner-city mothers, mother's age at delivery, independent of other characteristics of mother and child present early in the child's life, is a predictor of the child's self-sufficiency some 30 years later," the scholars wrote.

Both Hilton and Hardy emphasized, however, that their findings cannot be used to predict every individual's situation. Some of the study subjects achieved success despite being born to teen moms.

Of those born to teenage moms, 68 percent did not have children themselves until at least 20 years old, 62 percent received a high school diploma and 72 percent were financially independent of public support. Those born to older moms had even higher success rates.

One boy was born to a mother who started her family as a teenager. The boy's father was an alcoholic who frequently squandered his pay from sporadic jobs. The boy had to hold down part-time jobs after school to help his family put food on the table.

Nevertheless, the boy - when interviewed 30 years later - had achieved success by graduating not only from high school but also college, pursuing a career with a well-known national firm and fathering two children of his own after he was 20.

"Here was a kid who pulled himself up by his bootstraps, with a little help from his mother," Hardy said. "It's an example of one way to be successful."

While the study child managed to overcome difficult early circumstances, his three siblings - also born to a woman who became a mom as a teen - did not. During the recent round of interviews, one of the man's brothers was in jail, another was a severe alcoholic and his sister had became a teenage mother herself.