It’s not surprising that premature babies are less likely to survive compared to full-term infants, but what is groundbreaking news is that years after their birth, they stand a 38% increased risk of dying in young adulthood, according to research published Tuesday in the Journal of the American Medical Association.
Researchers at Stanford University looked at 674,000 Swedish babies born from 1973 to 1979, and found that 5% were born preterm, defined as earlier than 37 weeks’ gestation. The researchers then tracked these children until they were 29 to 36 years old.
Preterm infants had a 59% increased risk of death in early childhood (between ages 1 and 5), compared with babies born later. They succumbed to congenital anomalies — mostly heart defects — along with respiratory and endocrine problems.
The increased risk of death in early childhood has been backed up by previous research. But the Stanford study appears to be the first to track death risk into early adulthood, finding, contrary to popular belief, that it persists. Preterm babies who survived to age 18 to 36 then faced a 38% increased risk of death compared with their full-term peers, the researchers found, although the absolute risk was still small. Lead author Casey Crump, a clinical assistant professor of medicine at Stanford, called the results “quite remarkable.”
“We all know that preterm infants have a higher risk of dying in the first few years of life, but that risk was believed to wane over time,” says Crump. “This shows that an increased risk of mortality reappears in young adulthood. That’s important news for survivors of preterm birth, their families and their doctors.”
In practical terms, the findings suggest that former preemies should be followed more closely by their physicians. They should also take extra care to maintain a healthy lifestyle, eating well, exercising regularly and avoiding obesity and smoking.
“It’s important for people to be more aware of the potential for longer-term health effects of preterm birth,” says Crump. “These survivors need to be followed carefully.”
Although the findings sound scary, most survivors of preterm birth actually do very well. Despite the relative increase in risk of early death, the findings show that the absolute risk of death in early adulthood is low: less than one person per 1,000 preterm survivors.
Researchers detected no increase in death risk in late childhood and adolescence, perhaps because preterm infants who make it past the first year of life do relatively well through their teen years. It’s usually after adolescence that health problems such as heart disease get to the point that they present a problem.
The situation can be compared to cardiovascular disease and diabetes in the general population. “They can have serious health effects that accumulate over time, and perhaps the same thing is happening with preterm survivors,” says Crump.
Along those lines, Crump theorizes that the risk of early death will only compound as preterm survivors reach middle and older adulthood. “This highlights the need for better prevention of preterm birth,” says Crump.