THURSDAY, June 23 (HealthDay News) -- New research suggests that the adverse effects of pre-term birth can extend well into adulthood.

The latest findings, from a University of Rhode Island study that has followed more than 200 premature infants for 21 years, revealed that preemies grow up to be less healthy, struggle more socially and face a greater risk of heart problems compared to those born full-term.

One reason for this, explained study author Mary C. Sullivan, professor of nursing at the University of Rhode Island and adjunct professor of pediatrics at the Alpert Medical School at Brown University, is that extremely low birth weight, repeated blood draws, surgery and breathing issues can affect stress levels among pre-term infants.

She pointed out these stressors produce higher levels of the hormone cortisol, which is involved in the regulation of metabolism, immune response and vascular tone.

Among Sullivan's findings:

• The less a preemie weighs at birth, the greater the risk. Sullivan found preemies born at extremely low birth weight had the poorest pulmonary outcomes and higher resting blood pressure.
• Premature infants with medical and neurological problems had up to a 32 percent greater risk for acute and chronic health conditions vs. normal-weight newborns.
• Pre-term infants with no medical conditions, particularly boys, struggled more academically. Sullivan found that preemies tended to have more learning disabilities, trouble with math and need more school services than kids who were full-term babies.
• Some children born prematurely are less coordinated. This may be related to brain development and effects of neonatal intensive care, the researchers said.
• Premature infants also tended to have fewer friends as they matured, the team found.

The outlook isn't entirely bleak for premature infants, however. Infants who are born too soon are often resilient and have a strong will to succeed as they get older, the researchers found. And there are also certain "protective factors" that can help preemies overcome the negative issues associated with pre-term birth. Sullivan said that supportive parents and a nurturing school environment can mitigate the effects of premature birth.

The researchers concluded the ongoing monitoring of adults born prematurely is justified, and would also help scientists understand the impact of prematurity on adult health, particularly cardiopulmonary disease.

"These findings are important for parents, nurses in the neo-natal intensive care units, teachers and staff in the schools, disability services offices in colleges and primary care providers," Sullivan said. "By identifying the issues pre-term babies face in childhood, adolescence and through adulthood, we can all be better prepared to take steps to mitigate their effects."

The study's findings were slated for presentation in September at the 27th Congress meeting of the European Group of Pediatric Work Physiology in Exeter, England.

Because this study is to be presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.

More information

The U.S. National Institutes of Health provides more information on the complications of prematurity.