Premature boys age faster than those with normal birth weight, study suggests
EDMONTON -- Boys born weighing less than a kilogram are 4.6 years older biologically later in life than men of the same age who were born at a normal birth weight, according to a recent study by McMaster University researchers.
The study, published in the journal Pediatrics on Monday, suggests that accelerated aging may be influenced by physiological stress put on the baby in utero and, later, in the in the hospital neonatal intensive care unit after they are born.
Researchers at McMaster University have been following a group of “extremely low birth weight” (ELBW) babies and their normal weight counterparts since 1977 as part of the observational study.
Using an epigenetic clock – a biochemical test used to measure age – researchers looked at the genes of 45 men who were born prematurely and 47 men born at a normal birth weight between the ages of 30 to 35 to compare their biological age, controlling for chronic health problems and sensory impairments.
They found that men who were born prematurely aged more quickly and were approximately 4.6 years older biologically than those born at a normal birth weight.
“This cohort has been followed since the late 70’s, early 80’s, so we’ve met them many times and gotten to know them… and because they’re around my age, I noticed that some of the men, particularly, looked like they five or 10 years older,” Ryan Van Lieshout, first author of the study, told CTVNews.ca by phone last week.
Biological age is a measurement of physical age, instead of chronological age, based on various biomarkers — a number that can change due to lifestyle and other health factors.
Researchers hypothesized that the men who were born prematurely may be experiencing accelerated aging due to the stress that comes with a high-risk premature birth in utero and the extensive and high-stress health care that follows in their first months of life.
“Because of all of the stress that they were under both in the womb and in the post-womb period, when they'd be getting all of these life saving measures... we're starting to see that they're developing some health problems a little bit earlier,” said Van Lieshout.
Though more research needs to be done as the cohort ages, Van Lieshout says the evidence might predict that men born prematurely may be at a higher risk of chronic diseases later in life.
He notes that the study is not meant to be alarming, but more so a call to action for survivors of prematurity do the things that help us age in a healthy way, such as eating a healthy diet, exercising, avoiding smoking, and getting a good sleep.
"When these babies are born, they get as much medical intervention as any person does in the system,” he noted. “It’s important not only to save them in that time, but that we continue to monitor their health and support them during childhood, adolescence and even into adulthood.”
The study is the world’s longest longitudinal study of ELBW babies and included both male and female participants.
But, interestingly, the aging difference was not found between birth weight groups in the female participants – a finding that may reinforce the hypothesis that pre- and post-natal stress may be to blame.
According to the study, previous research has shown that the ELBW boys are more susceptible to prenatal stresses than ELBW girls and have worse outcomes than their female counterparts.
“Preemie males tend to have far worse outcomes at birth, so they tend to be smaller, they sometimes have a higher mortality rate, and more complications,” Van Lieshout explained.
“Girls usually have better outcomes, both in neonatal and then later in life as well. We hypothesize that that might be the reason that the men are aging in a more accelerated way than the female preemies or their normal weight male counterparts.”
Van Lieshout and his team will follow up with the cohort in their 40s to do a more comprehensive study to evaluate their aging and overall health.