NEW YORK Tue Nov 19, 2013 1:29pm EST

(Reuters Health) - Although babies who are born weighing less than 3.3 pounds face challenges early on, by adulthood many report doing well, according to a new study.

Growing up, those kids have an increased risk of physical and mental health problems, past studies have shown. They also tend to do worse in school than their peers and have a harder time socially.

But by the time they reach adulthood, many seem to have left those problems behind.

"It looks to us as if, despite many challenges early on and some functional issues, like myopia (nearsightedness), they do catch up," Dr. Brian A. Darlow said.

He led the study at the University of Otago, Christchurch in New Zealand.

Darlow and his coauthors checked in with 230 adults, age 22 or 23, who were born in New Zealand in 1986 at a very low birth weight - defined as less than 3.3 pounds.

Compared to a group of 69 adults who were born at healthy weights, the formerly small babies were still about 12 pounds lighter and 1.7 inches shorter.

They were also slightly less likely to have finished college or advanced training. More formerly small babies had lived on welfare at some point and more reported wheezing in the past year.

Babies born very small are usually premature or have growth restriction complications, so it makes sense that they would be prone to breathing issues. Lungs are the last organ system to fully develop in the womb.

But people in each group rated their self-esteem and satisfaction with life fairly equally. The formerly small babies were no more likely to have attention-deficit/hyperactivity disorder or obsessive compulsive disorder, according to results published in Pediatrics.

Those participants also scored similarly on measures of behavioral problems and were no more likely to have had depression or an anxiety disorder.

People in both groups smoked the same amount of tobacco and marijuana, on average, and fewer participants from the low birth weight group had used other illicit drugs.

"For me the most important message is that despite differences where they existed, these young people rated their own life functioning and quality of life no different from their peers," Darlow told Reuters Health. "They think they are doing okay so we should respect that."

One in ten very low birth weight babies had a moderate or severe disability of some kind at age seven or eight. That was a good predictor of which children would still be lagging behind as adults, he said.

Darlow said he would have liked the study to include more formerly normal-weight babies for comparison.

"What I personally find perhaps most alarming, and probably many of my colleagues would agree, is that a larger proportion of very low birth weight adults report having few or no friends," which fits with previous studies, Eero Kajantie told Reuters Health.

Kajantie studies premature birth and long-term health at the University of Helsinki in Finland.

About half of study participants born at a very low weight said they had few or no friends, compared to one-third of the healthy birth weight comparisons.

Only one or two percent of babies are born at a very low birth weight, but they make up half the population of neonatal intensive care units, according to the study.

"It is very rewarding to see that despite earlier difficulties, the majority of premature children have completed the basic educational requirements," Dr. Saroj Saigal said.

Saigal studies very low birth weight infants as they grow and age into adulthood at McMaster University in Hamilton, Ontario, Canada. She was not involved with the New Zealand study.

A significantly higher proportion of premature babies require special assistance at school, she said. If this assistance isn't available it can hamper their development.

But the new findings add to a growing body of evidence that once these babies reach adulthood, they do well.

"There is light at the end of the tunnel," Saigal told Reuters Health. "Parents and siblings can be reassured that the majority of very low birth weight young adults will be able to live independently."

"Realistic expectations and encouragement, family support and availability of resources at school can be helpful," she said.

SOURCE: Pediatrics, online November 18, 2013.

Copyright 2012 Thomson Reuters. Click for Restrictions.

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