Prematurity is defined as birth occurring before 37 full weeks of gestation. Advancements in neonatal medicine mean most premature infants now survive and thrive into adulthood. Despite improved survival, being born prematurely is recognized as a significant risk factor for various long-term health issues compared to those born at term. These challenges stem from the interruption of the final, rapid stages of fetal development, which affects the programming of several organ systems. A notable subset of adults born prematurely faces increased susceptibility to chronic disorders involving the cardiovascular, respiratory, metabolic, and neurodevelopmental systems.
Respiratory and Cardiovascular Health Outcomes
The respiratory system is particularly susceptible to long-term effects because lung development is often incomplete at birth, especially in extremely preterm infants. Adults born prematurely often show reduced overall lung capacity and exhibit signs of obstructive lung disease. Many demonstrate a persistent reduction in forced expiratory volume in one second (\(\text{FEV}_1\)), a key measure of lung function, even without a history of severe infant lung disease. This compromised function increases the lifetime risk of developing respiratory symptoms often reported as asthma. Furthermore, some adults born extremely preterm, particularly those with a history of bronchopulmonary dysplasia (BPD), meet the criteria for Chronic Obstructive Pulmonary Disease (COPD) in early adulthood.
Cardiovascular outcomes are also a major area of concern, as the heart and blood vessels were underdeveloped at the time of birth. Adults born prematurely have a higher prevalence of systemic hypertension, often detectable by early to mid-adulthood. Advanced imaging reveals subtle structural differences, including smaller ventricles and thicker heart walls, resulting in a heart that is less efficient at pumping blood. These structural and functional differences contribute to an increased risk of ischemic heart disease (IHD) later in life, with the risk rising as individuals enter their 30s and 40s. Reduced exercise tolerance is thought to be a combined consequence of altered heart structure and reduced lung function, suggesting significant long-term implications for overall physical endurance.
Neurodevelopmental and Cognitive Function
Preterm birth interrupts the crucial neurodevelopmental window of rapid brain growth during the final months of pregnancy. Consequently, adults born prematurely, especially those born very or extremely preterm, show a higher incidence of persistent cognitive challenges. These challenges often manifest as specific deficits in executive functions, which govern planning, organization, working memory, and attention. Increased rates of learning disabilities and Attention Deficit Hyperactivity Disorder (ADHD) are significantly more common in this population. Subtle differences in brain structure, particularly in the frontal and temporal lobes, are believed to underlie these difficulties with complex cognitive tasks and academic achievement.
There is also an elevated risk for certain mental health and social adjustment difficulties. Adults born preterm show increased vulnerability to conditions like anxiety and depression compared to the general population. Socially, some individuals may face challenges in social integration, affecting their ability to form partnerships or maintain employment. Even those born moderate or late preterm (32–37 weeks) show slightly poorer intellectual performance and a mildly increased risk for psychiatric disorders, including mood and substance use disorders.
Metabolic and Sensory System Implications
Premature birth deeply affects the metabolic system, leading to a predisposition for metabolic syndrome. Young adults born prematurely often show an altered body composition, including more fat tissue and fat deposits in organs like the liver, even with a normal body mass index. This accumulation of fat, particularly around the abdomen, is a significant marker for future metabolic disease. This altered composition is closely linked to an increased risk of developing insulin resistance, a precursor to Type 2 diabetes. The combination of metabolic changes and arterial hypertension further elevates the overall risk for early-onset cardiovascular disease.
Sensory System Deficits
Two sensory areas require lifelong monitoring: vision and hearing. The underdeveloped retina can lead to Retinopathy of Prematurity (ROP), which may cause long-term visual impairments such as visual perceptual impairment and a higher rate of needing corrective lenses. Hearing loss is also a recognized long-term consequence, with preterm infants facing a significantly higher risk compared to full-term infants. While modern screening programs have improved early detection, these sensory deficits may require ongoing management, impacting communication and quality of life.
The Influence of Gestational Age on Adult Risk
The severity of long-term health outcomes is strongly and directly related to the gestational age at birth. Risks are stratified based on the degree of prematurity. The highest risks for chronic disorders across all systems are concentrated in the extremely preterm group, defined as birth before 28 weeks of gestation.
For those born very preterm (between 28 and 32 weeks), the risks remain substantial but are less severe than the extremely preterm group. These individuals still require careful monitoring for conditions like hypertension and cognitive executive function deficits. In contrast, the majority of individuals born moderate or late preterm (between 32 and 37 weeks) experience minimal long-term adult complications. While small, measurable differences in health markers may be present, the absolute risk for major, life-altering chronic disease is low.