NEW YORK (Reuters Health) - A study of young adults born at very low birth weights suggests that certain deficits, such as lower IQ and academic achievement, persist beyond childhood.

On the other hand, these young adults were doing fairly well, despite having higher rates of impairments such as cerebral palsy and blindness, according to findings published in the January 17th issue of The New England Journal of Medicine.

Dr. Maureen Hack and her colleagues followed very low birth weight infants treated at Rainbow Babies and Children's Hospital in Cleveland, Ohio, between 1977 and 1979. They found that by the age of 20, certain deficits that had been relatively more common in this group at age 8 were still evident.

By age 20, 74% of the 242 in the group had graduated from high school. That compares with 83% of a group of normal birth weight individuals who were also followed from birth. The average IQ and scores on academic tests were also lower in the low birth weight group, according to the report.

Since the introduction of neonatal intensive care units in the 1960s in the US, more and more extremely low birth weight infants have been surviving. But these tiny babies are at increased risk of impairments such as cerebral palsy. And research has shown that even when they have normal intelligence, these children may have more learning problems and poorer performance in school.

The 20-year-olds in the current study were born prematurely--around the 30th week of pregnancy, on average. A full term pregnancy is 40 weeks. Their average birth weight was 1,179 grams, or a little more than 2.5 pounds.

Ten percent had some sort of neurological or sensory impairment, compared with less than 1% of the normal birth weight group, the report indicates.

These results, the researchers write, suggest that the developmental and academic problems that have been found among very low birth weight children ``persist into young adulthood.''

But despite their difficulties, these young adults were less prone to risky behavior, the investigators found. They were less likely to use alcohol or marijuana, and males were less likely than their normal birth weight peers to get in trouble with the police over truancy from school or alcohol and drugs. Females of low birth weight were less likely to have had sex or been pregnant.

``The fact that the preemies have lesser risk-taking is very encouraging,'' Hack told Reuters Health.

This finding is ``new and striking,'' according to an editorial published with the report.

While academic problems are not unexpected among these children, ``what is unexpected is their relative success despite such difficulties,'' write Dr. Marie C. McCormick of Harvard School of Public Health and Dr. Douglas K. Richardson of Beth Israel Deaconess Medical Center, both in Boston, Massachusetts.

``Many of these adolescents have academic achievement at least equal to that of their normal birth weight peers,'' the editorialists note.

Still, they point out, research needs to pinpoint the environmental factors that determine the outcomes for children born at a very low weight so that more can be done to prevent the problems seen in this study.

Hack said that her team has not yet looked at all of these potential factors, but did, in this study, account for influences such as mothers' education and marital status.

SOURCE: The New England Journal of Medicine 2002;346:149-157, 197-198.

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