Babies who are born too soon may be more likely to develop heart disease as adults than full-term infants, a new study suggests.
Adults who were born before 37 weeks gestation were 53 percent more likely to develop heart disease than people who were full-term babies, researchers found. And people who’d been born just a little bit early - at 37 to 38 weeks gestation - were 19 percent more likely to develop heart disease.
Pregnancy normally lasts about 40 weeks, and babies born after 37 weeks of gestation are considered full-term. Babies born prematurely - earlier than 37 weeks - often have difficulty breathing and digesting food in the weeks after birth. Preemies can also encounter longer-term challenges such as impaired vision, hearing and cognitive skills, as well as social and behavioral problems.
Preterm birth has also been linked to an increased risk of high blood pressure and diabetes decades later. But research to date hasn’t conclusively linked an early delivery to an increased risk of so-called ischemic heart disease, which happens with the arteries narrow and limit how much blood and oxygen reach the heart.
For the current study, researchers examined data on more than 2.1 million babies born in Sweden between 1973 and 1994, following them through 2015 to see how many developed heart disease. Only 1,921 of these babies, or less than one percent, went on to be diagnosed with heart disease by ages 30 to 43.
“Preterm birth interrupts the development of the cardiovascular system and other organs, leading to abnormal structure or function of blood vessels and other disorders such as diabetes that can lead to heart disease,” said lead study author Dr. Casey Crump of the Icahn School of Medicine at Mount Sinai in New York City.
“Our findings were not explained by maternal factors that might contribute to both preterm birth and future heart disease, such as obesity, hypertension, diabetes, and smoking,” Crump said by email. “In addition, we also compared persons born preterm with their siblings who were not, which suggested that the findings were not explained by other risk factors shared within families, but were more likely from direct effects of preterm birth.”
For every 100,000 babies born at full term each year, about 5.9 would develop heart disease as adults, researchers calculated. That compares to about 6.5 of every 100,000 babies born slightly early and 8.8 of every 100,000 preemies.
One limitation of the study is that researchers lacked more detailed clinical data needed to verify the heart disease diagnoses, the study authors note. They also had too few extremely preterm babies to draw firm conclusions about the heart risks associated with delivery earlier than 34 weeks gestation.
Another drawback is that the follow-up period was too brief to detect differences in heart disease rates later in adulthood, when the condition is more commonly diagnosed.
Even so, the results suggest that adults born even a little bit early should take extra precautions to protect the heart, said Dr. Thuy Mai Luu of the University of Montreal and CHU Sainte-Justine in Canada, who co-authored an editorial published with the report.
“Some risk factors associated with cardiovascular diseases can be prevented through healthy lifestyle habits including a diet rich in fruits and vegetables, reduced sedentary time, regular physical activity and avoidance of primary and secondary smoke exposure,” Luu said by email.
“This is important to all, but maybe more so for children and adults born preterm,” Luu added. “Given that it is hard to change behaviors, adopting a healthy lifestyle early in childhood is crucial; parents are central to this.”