Feb 4:A longitudinal study by researchers at Vilnius University’s Faculty of Medicine shows that nearly 80 percent of all diagnoses in children born prematurely are identified before the age of seven, underscoring the need for early, long-term and personalised follow-up care.
Analysing health trajectories from birth to adulthood, Dr Rūta Morkūnienė and Prof. Dr Janina Tutkuvienė demonstrate that the health impact of prematurity extends far beyond infancy. The finding has global relevance: according to the World Health Organisation, around 15 million babies worldwide are born preterm each year. While survival rates have improved dramatically, the study reveals that the first seven years of life are critical for identifying health risks, challenging the assumption that prematurity-related problems are confined to the neonatal period and highlighting the importance of sustained, multidisciplinary monitoring as children grow.
Most health risks emerge early in life
The study is one of the most comprehensive analyses of long-term health outcomes in children born preterm conducted in Lithuania to date. Drawing on medical records from primary healthcare institutions, Dr Morkūnienė examined the health status of children born prematurely from birth through adolescence.
Unlike many earlier studies, the research did not limit itself to conditions traditionally associated with prematurity, such as respiratory or neurological disorders.
“I did not set out to record only diagnoses that are already described in the literature as typical for preterm children,” explains Dr Morkūnienė, a physician and lecturer at Vilnius University’s Faculty of Medicine. “I documented everything that each child accumulated over time. What emerged was a very broad spectrum of conditions, often involving multiple organ systems and differing greatly from one child to another.”
The findings show that children born prematurely experience a significantly higher overall disease burden than those born at term. Congenital anomalies, nervous system and mental health disorders, tumours, and diseases of the urinary and reproductive systems are diagnosed three to four times more often than the general population. Disorders of the immune and blood systems occur up to ten times more frequently, indicating a vulnerability that extends well beyond early childhood.
A critical window from birth to age seven
One of the study’s most striking results concerns when health problems tend to appear.
“More than 45 percent of all diagnoses are made during the first three years of life,” notes Dr Morkūnienė, “and over 30 percent more are identified between the ages of three and seven. In practical terms, this means that by the age of seven, children born prematurely have already accumulated nearly 80 percent of all diagnoses they will receive by adulthood.”
The heaviest disease burden falls on children born with very low birth weight (below 1,500 grams). These children not only develop more health conditions overall, but also a wider variety of them.
“We found that children born at the same gestational age and with the same birth weight do not necessarily follow similar health trajectories,” adds Dr Morkūnienė. “Each case is individual. Still, the most premature and smallest infants tend to accumulate both more numerous and more diverse health problems.”
Birth weight outweighs gestational age
A key methodological choice in the study was to analyse birth weight and gestational age separately, rather than treating them as a single combined indicator. This distinction revealed an important pattern.
The results show that birth weight has a stronger association with long-term disease burden than gestational age alone. Children born with lower birth weight grew more slowly and remained shorter and lighter than their peers into adolescence. Their body mass index (BMI) was initially lower, but from around the age of nine it began to rise rapidly, eventually exceeding that of children born at term.
“This pattern is increasingly recognised internationally,” explains Prof. Tutkuvienė, professor at Vilnius University’s Faculty of Medicine. “Children born prematurely are more likely to develop long-term metabolic risks, including obesity, diabetes and other metabolism-related disorders later in life. Unlike most previous studies, which analyse prematurity and birth weight together, our research examined these factors separately. This allowed us to identify which of them is more relevant for specific long-term metabolic processes – a key novelty of the study.”
Why population-specific growth standards matter
Beyond individual outcomes, the study also highlights a broader clinical challenge: the reliance on outdated or poorly adapted growth standards.“Until recently, Lithuania did not have head circumference reference values for newborns,” notes Dr Morkūnienė, “and the height and weight standards in use were based on limited or decades-old data.”
Using advanced statistical methods developed by Prof. Tim Cole (UCL Institute of Child Health, UK), the research team established new, population-specific growth norms for Lithuanian newborns, including preterm infants.
According to the researchers, international standards, while useful for comparison, can misrepresent clinically important thresholds in specific populations. In practice, this may lead to delayed or inaccurate diagnoses. The findings point to a global issue in neonatal and paediatric care: growth assessment must be locally valid in order to guide meaningful clinical decisions.
Survival is not the endpoint
Survival rates for preterm infants have improved dramatically. In Lithuania, nine out of ten children born prematurely now survive, placing the country among the most advanced globally in this respect. However, the researchers stress that survival alone should not be considered the final goal.
“Prematurity is not a life sentence,” emphasises Prof. Tutkuvienė. “The human body is resilient and capable of adaptation. What truly matters is whether health systems provide timely, personalised and long-term support that allows children to develop their full potential.”
Children born preterm, the researchers argue, require extended and more frequent follow-up delivered by multidisciplinary teams. These should include not only neonatologists and neurologists, but also psychologists, speech therapists, physiotherapists and other specialists who can monitor development across physical, cognitive and emotional domains.
“The earlier developmental difficulties are identified, the more can be achieved through early intervention,” stresses Dr Morkūnienė. “At this stage, a child’s development is still highly flexible and responsive to support. Timely assistance can significantly influence later outcomes, because early childhood is precisely the period when many functions can still be effectively corrected or strengthened.”