Most preemies are healthy in adulthood

More than half of premature infants grow up to be healthy adults without chronic medical issues, a new study suggests.

Researchers followed 2.56 million babies born in Sweden between 1973 and 1977 until they were 30 years old on average, including about 149,000 premature infants. Each decade, preemies’ odds of survival to adulthood improved, from about 91% of preterm infants born in the 1970s to about 96% of those born in the 1990s.

About 55% of preemies in the study had no serious chronic physical or mental health issues by early adulthood, compared 63% of full-term babies, researchers report in JAMA.

“Our findings reflect the apparent resilience of preterm birth survivors in maintaining good health,” said Dr. Casey Crump, lead author of the study and a researcher at the Icahn School of Medicine at Mount Sinai in New York City.

“Despite increased risks of several chronic disorders, the majority can still have good overall health in adulthood,” Crump said by email.

Pregnancy normally lasts about 40 weeks, and babies born after 37 weeks are considered full-term. In the weeks immediately after birth, preemies often have difficulty breathing and digesting food. Some premature infants also encounter longer-term challenges such as impaired vision, hearing and cognitive skills as well as social and behavioral problems.

In the current study, researchers focused on chronic health issues that typically develop in adolescence and young adulthood like asthma, high blood pressure, diabetes and mental health issues, as well as certain health problems that can surface later like chronic lung, kidney, and liver diseases.

Just 22% of extremely preterm babies - those born at 22 to 27 weeks gestation - were alive without any serious chronic health problems by the end of the study. But rates of this outcome got steadily better with more time in the womb.

About 49% of very preterm babies - born at 28 to 33 weeks - and 58% of late preterm infants - born at 34 to 36 weeks - were alive and generally healthy by early adulthood, the study found.

These outcomes were similar for men and women.

Even though the study followed babies until they were 30 years old on average, it’s still possible that starker differences between preemies and full-term infants might show up later in adulthood, the study team notes. Results from Sweden, which has a national health care program, may also not represent what would happen in other countries.

There isn’t necessarily anything preemies should do differently than full-term babies to minimize their risk of developing chronic physical or mental health problems later in life, said Dr. Lex Doyle, a professor of neonatal pediatrics at the University of Melbourne in Australia.

“Anyone born preterm does not need to be worried more because of this publication,” Doyle, who wasn’t involved in the study, said by email.

“They either will or will not have any of the chronic disease listed - if they do, they should seek medical advice and care,” Doyle added. “In terms of preventing chronic health problems, there is nothing the people born preterm should do that is any different to what we all should do - eat well, exercise, and don’t smoke.”