Infants born prematurely develop as well as peers by adolescence: study

By Mark Waghorn via SWNS

Infants born prematurely develop as well as their peers by adolescence, according to new research.

A large scale study found they reach a similar body mass index (BMI) - and are just as susceptible to becoming overweight or obese.

It allays fears they are at a physical disadvantage. The findings are based on an analysis of 253,810 individuals in eleven countries.

Lead author Johan Vinther, of the University of Copenhagen in Denmark, said: "This study based on data from infancy through adolescence found gestational age may be important for body size in infancy, but the strength of association attenuates consistently with age."

His team pooled data from 16 studies across the world, including the UK.

Vinther said: "By adolescence, preterm individuals have on average a similar mean BMI to peers born at term."

Around 60,000 babies are born before 37 weeks of pregnancy in the UK every year - equating to one in every thirteen.

In 2021, a record one in 10 infants were born prematurely in the US last year.

Rising rates of obesity and associated conditions such as type 2 diabetes are thought to be behind the rise, as well as the strain on healthcare services due to the COVID-19 pandemic.

Experts have claimed it leaves them at higher risk of physical and mental problems.

Conditions and exposures in early life is suggested to play an important role in development of cardiometabolic health outcomes, including body size.

Vinther said: "The majority of previous research focused on the impact of size at birth, that is birthweight, rather than the timing of birth, or gestational duration.

"Moreover, we know less about how different contextual factors influence associations between early life risk factors and later body size.

"Our aim was to examine the association of gestational age with BMI and overweight from infancy through adolescence."

The researchers included cohorts in Europe, the US and Australasia.

Vinther said: "We found infants born preterm, before 37 completed weeks of gestation, have a lower BMI and lower risk of overweight in infancy than their term counterparts and that this difference attenuates with age.

"In adolescence, BMI was similar between preterm and term peers, while there was an indication of an increased risk of overweight in very preterm individuals."

Globally, one in ten infants are born premature which raises the risk of the newborn dying or being left with health issues that may persist and develop over the life-course.

Vinther said: "Our study suggests that, although being born early, preterm infants on average reach the body size of their term peers before adulthood."

In line with earlier findings, children born very preterm may even be at increased risk of overweight in adulthood.

Vinther said the study sheds fresh light on factors influencing BMI and risk of developing overweight from infancy through adolescence.

He added: "Our analysis revealed that, although preterm infants are relatively small at birth, they reach similar BMI and odds of overweight as term peers in adolescence.

"The underlying mechanisms from the current observational data are unknown.

"However, in accordance with previous findings, our pattern of results suggests preterm infants maybe at an increased odds of overweight later in life, even though BMI in preterm and full term is similar.

"In addition, it should be noted mediating exposures such as birthweight, congenital anomalies and breastfeeding practices may also affect the relationship between gestational age and later body size."

The study was published in the journal PLOS Medicine.