Premature Infants are babies born before 37 completed weeks of gestation. Prematurity is further classified by gestational age because the degree of developmental immaturity strongly affects clinical needs. Babies born at the earliest gestations have substantially greater risks of respiratory, neurological, gastrointestinal, visual and developmental complications than those born closer to term. Birth weight is related to, but distinct from, gestational age; a small-for-gestational-age infant can be born at term, while a premature infant can have a weight appropriate for its gestational age. Prematurity is therefore defined primarily by timing of birth rather than weight alone.
Premature Infants have physiological characteristics that reflect incomplete maturation. The lungs may produce insufficient surfactant, making breathing difficult, while immature respiratory control can cause episodes of apnoea. Skin is thinner and provides less effective insulation, increasing heat loss. The gastrointestinal tract may be immature, and coordination of sucking, swallowing and breathing may not yet be sufficiently developed for safe and efficient oral feeding. Immature immune function increases susceptibility to infection. The severity of these issues depends strongly on gestational age, but individual variation is substantial.
Respiratory support is frequently required for very premature Infants. Treatment can involve continuous positive airway pressure, other non-invasive methods, surfactant replacement or mechanical ventilation. Clinicians carefully balance oxygen delivery because prolonged excessive oxygen exposure can contribute to complications, while insufficient oxygenation can damage developing organs. Apnoea of prematurity can occur because respiratory control centres are immature and may require monitoring, stimulation or medication in selected infants. As the lungs mature, respiratory support can usually be reduced, although some extremely premature infants develop chronic lung disease requiring longer-term follow-up.
Nutrition is particularly important for Premature Infants because they grow rapidly outside the uterus while having limited energy reserves and immature feeding abilities. Mother's own expressed milk is generally highly valued in neonatal care, and donor human milk may be used where available. Some infants require tube feeding until they can coordinate oral feeding, while very premature babies may initially need parenteral nutrition. Human milk may require fortification to provide sufficient protein, minerals and energy for certain premature infants. Feeding advancement is monitored carefully because immature intestines can be vulnerable to serious complications such as necrotising enterocolitis.
Premature Infants are at increased risk of necrotising enterocolitis, a serious inflammatory disease of the intestine that can cause bowel injury, perforation and systemic illness. The precise mechanisms are complex and involve intestinal immaturity, microbial interactions, inflammation and feeding-related factors. Clinical signs can include abdominal distension, feeding intolerance, bloody stools and systemic deterioration. Management may involve stopping enteral feeds, providing intravenous nutrition, antibiotics and intensive monitoring, while surgery may be required when perforation or severe intestinal damage occurs. Prevention and early recognition are important components of neonatal practice.
The developing brain of Premature Infants is vulnerable because important stages of neurological development occur during late gestation. Complications such as intraventricular haemorrhage and white-matter injury can affect neurological outcomes, while severe illness, infection and unstable oxygenation can also influence development. Neurodevelopmental follow-up may assess movement, language, cognition, hearing, vision and behaviour over time. Early developmental support can identify emerging difficulties and provide intervention when appropriate. Not every premature infant develops disability, and outcomes vary widely according to gestational age, complications, medical care and individual developmental trajectories.
Premature Infants can experience specific visual risks because retinal blood vessels develop rapidly during late gestation. Retinopathy of prematurity results from abnormal retinal vascular development and can become vision-threatening in severe cases. Screening is targeted to infants meeting relevant gestational-age, birth-weight or clinical criteria according to local protocols. Other longer-term considerations include hearing, growth, respiratory health, bone mineralisation, anaemia and neurodevelopment. Follow-up therefore extends beyond discharge from Neonatal Care because some effects of prematurity become apparent only as development progresses.
Premature Infants demonstrate why gestational age is a major determinant of neonatal physiology but not a complete predictor of an individual's outcome. Advances in respiratory support, nutrition, infection management, antenatal care and neonatal intensive care have improved survival for increasingly premature babies, although extremely early birth can still involve substantial risks. Families may require prolonged hospital support and coordinated follow-up after discharge. Care often transitions from intensive neonatal treatment towards developmental surveillance, feeding support and ordinary paediatric care as the infant matures. The term therefore encompasses a broad spectrum ranging from infants needing minimal specialised support to those requiring prolonged intensive care.
