Prematurity and common complications

01OverviewDefinition, clinical context and the essential points that orientate the chapter.

Prematurity interrupts maturation of every organ system. The infant must exchange gas, maintain temperature and glucose, coordinate feeding, regulate cerebral blood flow and resist infection before the biological systems supporting those tasks are ready.

Gestation is the strongest organising variable, but birth weight, fetal growth restriction, antenatal corticosteroid exposure, infection, delivery events and postnatal illness modify outcome. A 30-week growth-restricted infant and a healthy 30-week infant do not have identical risks.

Early protective care includes antenatal and delivery planning, temperature control, gentle respiratory support, appropriate oxygen, infection prevention, early human milk, nutritional support, minimal handling and developmentally supportive family-centred care.

Respiratory distress syndrome reflects surfactant deficiency. Bronchopulmonary dysplasia describes ongoing oxygen or respiratory-support dependency at a defined postmenstrual age and represents arrested lung development plus inflammatory and ventilator-related injury.

Apnoea of prematurity arises from immature central respiratory control and upper-airway stability. It improves with advancing postmenstrual age, but a new or worsening pattern is a symptom requiring reassessment.

Fragile germinal-matrix vessels, impaired autoregulation and haemodynamic fluctuation predispose to intraventricular haemorrhage. White-matter injury and altered brain development can occur without dramatic early examination findings.

Immature gut barrier, dysbiosis, inflammation and ischaemia contribute to necrotising enterocolitis. Human milk is protective, whereas clinical deterioration must be treated promptly because progression can be rapid.

Family participation, skin-to-skin care where stable, support for milk expression and honest communication are clinical interventions. Long admissions can affect bonding, parental mental health and confidence as well as infant outcomes.

Long-term risk includes motor, cognitive, language, behavioural, hearing, visual, respiratory, feeding and growth difficulties. Structured surveillance detects problems early but must not replace response to concerns between scheduled reviews.

Key points

Preterm birth is before 37 completed weeks; risk and immaturity rise steeply at lower gestation, so use exact gestational and postmenstrual age rather than the label premature alone.
Immature lungs have reduced surfactant and compliant chest walls, immature respiratory drive and vulnerability to oxygen and ventilation injury.
Maintain a neutral thermal environment, minimise evaporative heat loss and monitor glucose because small glycogen and fat stores make hypothermia and hypoglycaemia common.
Use breast milk, lactation support and unit-specific fortification; advance enteral feeds carefully while providing parenteral nutrition when full intake is not yet possible.
Apnoea of prematurity is a diagnosis of exclusion. Caffeine citrate is routine in babies born at or before 30 weeks and is used for clinically significant recurrent apnoea.
Necrotising enterocolitis presents with feed intolerance, distension, blood in stool and systemic illness; stop feeds, decompress, investigate, treat sepsis and involve surgery early.
Intraventricular haemorrhage can be silent. Follow gestation- and risk-based cranial ultrasound schedules and trend head circumference and neurological state.
Retinopathy screening includes babies born before 31 weeks or weighing below 1501 g; consider screening at 31+0 to 31+6 weeks according to the national guideline.
After stabilisation, NICE recommends a preterm oxygen-saturation target of 91–95%; both hypoxia and excess oxygen cause harm.
Assess development using corrected age until 2 years. Babies below 28 weeks also receive a face-to-face developmental assessment at 4 years uncorrected age.
Plan immunisation by chronological age unless a specific programme says otherwise, and give eligible seasonal respiratory-virus prevention according to the current national programme.
Discharge requires physiological stability, safe feeding and growth, family training, medication and equipment plans, screening completion and coordinated neonatal/community follow-up.

02AetiologyUnderlying causes, associations and risk factors, with why each one matters.

Spontaneous preterm labour

Inflammation, membrane rupture, cervical insufficiency, uterine overdistension and placental pathology can trigger labour before fetal maturation is complete.

Medically indicated birth

Maternal pre-eclampsia, haemorrhage, severe illness, fetal compromise or growth restriction may make early delivery safer than continuing pregnancy.

Risk modifiers

Previous preterm birth, multiple pregnancy, infection, smoking, socioeconomic adversity and uterine or cervical factors alter risk, although many births have no single cause.

03PathophysiologyThe causal sequence from the underlying abnormality to symptoms and harm.

1
Immature gas exchange
Surfactant deficiency, compliant chest wall, small airways and immature drive promote atelectasis, ventilation-perfusion mismatch, fatigue and apnoea.
2
Vulnerable brain circulation
Fragile germinal-matrix vessels and weak autoregulation make abrupt changes in pressure, carbon dioxide and venous return hazardous.
3
Immature gut and immunity
Weak mucosal defence, altered microbiota and inflammatory responses increase infection and necrotising-enterocolitis risk, especially during systemic instability.
4
Interrupted organ development
Extrauterine oxygen, inflammation, nutrition and treatment interact with unfinished lung, retinal, renal and neural maturation to create later morbidity.

04Clinical features and red flagsSymptoms, examination findings, patterns of presentation and time-critical warnings.

Perinatal risk profile

Document best obstetric gestation, birth weight and centile, sex, antenatal exposures, membrane rupture, infection risk, corticosteroids, magnesium sulphate and delivery/resuscitation details.

Whole-infant trajectory

Assess work of breathing, respiratory pauses, oxygen and pressure requirement, perfusion, temperature, glucose, tone, movement, abdominal state, feeds, urine and stool trends rather than single values.

Gestation-specific physiology

Interpret heart rate, blood pressure, gases, haemoglobin and electrolytes against gestation, postnatal age, respiratory support and trajectory; adult normal ranges are unsafe.

Growth pattern

Track weight, length and head circumference on appropriate preterm charts and distinguish expected early weight loss from dehydration, insufficient intake or disease.

Developmental history

At follow-up ask directly about vision, hearing, feeding, sleep, respiratory symptoms, movement, language, behaviour and family wellbeing; use corrected age when judging milestones to 2 years.

Developmental examination

Examine tone, posture, symmetry, spontaneous movements, head growth, hips, eyes, hearing responses and cardiorespiratory status, escalating loss of skills or persistent asymmetry.

Red flags requiring action

Recurrent apnoea with bradycardia or desaturation is not automatically apnoea of prematurity; exclude sepsis, respiratory deterioration, anaemia, metabolic disturbance and seizures.
Abdominal distension, bilious or bloody aspirate, blood in stool, tenderness, discoloration or systemic instability raises necrotising enterocolitis and requires feeds to stop immediately.
A bulging fontanelle, seizures, sudden anaemia, hypotonia or unexplained cardiorespiratory deterioration raises intraventricular haemorrhage or evolving post-haemorrhagic ventricular dilatation.
Increasing oxygen or ventilatory requirement may reflect respiratory distress syndrome, air leak, infection, patent ductus arteriosus or evolving bronchopulmonary dysplasia.
Absent red reflex, abnormal visual behaviour or failure to complete retinopathy screening risks preventable visual loss.
Poor growth, persistent feeding difficulty, abnormal tone, asymmetry, loss of skills or parental developmental concern needs assessment rather than reassurance based only on corrected age.

05InvestigationsWhat to request, why it matters and how to interpret it.

Investigation order

Read from the initial assessment onwards. Tests may run in parallel in urgent care; first-line, preferred, confirmatory, definitive and gold-standard labels appear only when the chapter explicitly states them.

01
First-line: continuous physiological monitoringFirst stepFirst line
Why
Detect hypoxaemia, apnoea, bradycardia, temperature disturbance and haemodynamic change in babies requiring neonatal care.
Interpretation and limitations
Interpret trends and artefact in clinical context; after stabilisation target oxygen saturation 91–95% for preterm babies unless a specialist indication changes the target.
02
Blood gas, glucose, FBC, CRP, cultures and biochemistry when clinically indicated
Why
Evaluate respiratory failure, metabolic instability, anaemia, infection, renal function and electrolyte disturbance.
Interpretation and limitations
Sampling should answer a question and minimise iatrogenic blood loss; a reassuring single inflammatory marker does not exclude early infection.
03
Chest radiograph or lung ultrasound
Why
Clarify respiratory distress, line or tube position, air leak and evolving lung disease when examination and response are insufficient.
Interpretation and limitations
Diffuse low-volume granular change supports RDS; focal change, hyperinflation or an air leak shifts the differential, but imaging never substitutes for immediate stabilisation.
04
Protocol cranial ultrasound
Why
Screen high-risk preterm infants for intraventricular haemorrhage, ventricular dilatation and later white-matter injury.
Interpretation and limitations
Timing and repetition depend on gestation and findings; serial change is more informative than an isolated scan and MRI may refine term-equivalent prognosis.
05
Reference programme: ROP retinal examination
Why
Identify treatable retinal vascular disease before irreversible detachment or visual loss.
Interpretation and limitations
Screen all babies born before 31 weeks or below 1501 g and consider 31+0 to 31+6 weeks; timing and treatment follow the RCPCH/RCOphth programme.
06
Developmental and sensory assessment
Why
Detect cerebral palsy, language, cognitive, behavioural, hearing, visual and feeding difficulties early.
Interpretation and limitations
Use corrected age to 2 years and validated tools within enhanced surveillance; abnormal general movements, persistent asymmetry or regression prompts specialist assessment.

06Differential diagnosisRealistic alternatives and the features that help distinguish them.

Sepsis

Temperature instability, apnoea, feed intolerance and poor perfusion overlap with prematurity but a new trajectory requires infection assessment.

Cardiorespiratory disease

RDS, air leak, congenital heart disease, PDA and anaemia can each drive oxygen need or apnoea and need directed evaluation.

Neurological or metabolic disease

Seizures, intracranial haemorrhage, hypoglycaemia and electrolyte disturbance may appear as pauses, hypotonia or altered responsiveness in preterm infants.

Normal immature pattern

Periodic breathing and slow feeding coordination can be developmental, but only when physiology, growth and serial assessment remain reassuring.

07ManagementImmediate care, first-line treatment, alternatives and escalation.

01At birthProtect transitionFirst stepPreterm birth is expected or has occurred.

1Arrange appropriately skilled neonatal attendance and antenatal counselling.
2Prevent heat loss, support lung aeration gently and titrate oxygen by preductal saturation.
3Admit to the appropriate level of neonatal care and establish nutrition, monitoring and family contact.

02DeteriorationReassess the diagnosisApnoea, oxygen need, perfusion, feeds, abdomen, temperature or behaviour worsens.

1Stabilise ABC, temperature and glucose and call senior neonatal help.
2Consider sepsis, NEC, respiratory disease, PDA, anaemia, metabolic disturbance, neurological injury and equipment problems.
3Obtain focused tests and start time-critical treatment; do not attribute new deterioration to prematurity alone.

03Ongoing carePrevent secondary injuryThe infant is stable enough for planned neonatal care.

1Use human milk, careful nutrition, infection prevention and developmentally supportive handling.
2Follow respiratory, cranial ultrasound, hearing, blood-spot and ROP pathways.
3Minimise painful procedures, unnecessary oxygen, ventilation, transfusion and antimicrobial exposure while treating genuine disease promptly.

04DischargeBridge hospital and homeThe infant approaches physiological maturity and no longer needs inpatient support.

1Confirm stable temperature, respiratory control, feeding and growth and complete car-seat or home-oxygen assessment where indicated.
2Teach medicines, emergency signs, equipment use and safe sleep; reconcile screening and immunisation.
3Provide a named follow-up plan using corrected age, with neonatal, primary-care, therapy and safeguarding contacts.

Key medicines and prescribing safety1 treatment · regimens, roles and cautions

First-line pharmacological treatment for apnoea of prematurity; give routinely as soon as possible after birth to babies born at or before 30 weeks, ideally before 3 days.

Caffeine citrate

Loading dose 20 mg/kg caffeine citrate intravenously over 30 minutes once. Start maintenance 24 hours later at 5 mg/kg once daily IV or enterally; NICE permits specialist increase up to 20 mg/kg daily according to response and local neonatal protocol.

This is caffeine citrate, equivalent to half the dose as caffeine base. Use current weight and neonatal prescribing safeguards; monitor tachycardia, feeding intolerance and seizures. NICE suggests stopping at 33–35 weeks corrected gestation when stable.

08ComplicationsImportant consequences, why they occur and why they matter clinically.

Respiratory morbidity

RDS, air leak, apnoea and bronchopulmonary dysplasia can prolong support and increase later wheeze, infection and readmission.

Brain and developmental injury

IVH, white-matter injury and disrupted development increase cerebral palsy, cognitive, language, sensory and behavioural difficulties throughout childhood.

Gastrointestinal and nutritional harm

NEC, parenteral-nutrition cholestasis, oral aversion and poor growth may have serious surgical, nutritional and long-term developmental consequences.

Sensory disease

ROP and hearing impairment can be subtle initially but materially affect development unless screening, treatment and habilitation occur promptly.

09Monitoring and follow-upTreatment response, safety checks and longer-term review.

Trend respiratory support, oxygen exposure, apnoea and caffeine response; reassess every new cluster rather than simply increasing alarms.
Monitor temperature, glucose, fluid balance, electrolytes, renal function, weight and head circumference at a frequency appropriate to gestation and illness.
Review feed tolerance and abdominal examination before escalation; document human-milk provision, fortification and parenteral-nutrition complications.
Follow haemoglobin, transfusion exposure, infection episodes, line days and antimicrobial courses while minimising sampling and invasive-device harm.
Complete national newborn, hearing and ROP screening and gestation/risk-based brain imaging; record outstanding actions explicitly at transfer or discharge.
Enhanced developmental surveillance includes reviews at 3–5 months corrected age, by 12 months and a detailed assessment at 2 years corrected age for eligible infants.
All children born before 28 weeks should have the recommended face-to-face assessment at 4 years uncorrected age, with rapid referral when concerns arise earlier.

10Special situationsVariants, exceptions and circumstances that change the usual approach.

Corrected age

Subtract the number of weeks born before 40 weeks from chronological age when assessing development until 2 years; immunisation still usually follows chronological age.

Apnoea is a sign

Prematurity explains a characteristic pattern only after infection, respiratory failure, seizures, anaemia, hypoglycaemia and temperature disturbance have been considered.

Human milk is treatment

Mother's own milk, supported expression and donor milk where indicated provide nutritional and infection-related benefits beyond simple calorie delivery.

Oxygen has two edges

Insufficient oxygen injures organs, while excessive oxygen contributes to retinal and lung injury; prescribe a target and respond to trends.

Parents hold longitudinal data

A family noticing altered movement, feeding or behaviour may detect change before a scheduled test, and their observations deserve explicit assessment.

11Common pitfallsFrequent interpretation and management errors.

01
Do not label recurrent apnoea as benign without checking the baby and excluding a new cause.
02
Do not use adult or term-infant reference ranges for a very preterm baby.
03
Do not chase saturation to 100%; prescribe and maintain the gestation-appropriate range.
04
Do not continue feeds through suspected necrotising enterocolitis while awaiting imaging.
05
Do not postpone ROP screening because the infant has transferred; responsibility and appointment must be handed over explicitly.
06
Do not assess milestones by chronological age alone before 2 years or dismiss regression as prematurity.
07
Do not assume discharge ends neonatal risk; reconcile medicines, oxygen, nutrition, immunisation, screening and follow-up.
08
Do not exclude parents from decisions or overlook trauma, anxiety and practical barriers created by a prolonged neonatal admission.