Adolescents who were born extremely premature are much more likely to have chronic health problems than their peers who were delivered at full term, a Swedish study suggests.

Pregnancy normally lasts about 40 weeks, and babies born after 37 weeks are considered full term. The study focused on extremely preterm infants, delivered at 23 to 25 weeks gestation.

In the weeks immediately after birth, these early arrivals often have difficulty breathing and digesting food. They can also encounter longer-term challenges such as impaired vision, hearing, and cognitive skills as well as social and behavioral problems.

“Children born extremely preterm at 23 to 25 weeks gestation face an increased risk of chronic health problems such as neurodevelopmental handicap (mostly mild or moderate), asthma, and behavioral difficulties,” said study co-author Dr. Aijaz Farooqi, a researcher at the University Hospital of Umea in Sweden. At school age, many extremely preterm children whose general intelligence is normal or in the lower normal range have motor impairments, behavioral problems, social problems and academic underachievement,” Farooqi added by email.