Outcome after Preterm Birth

Outcome after Preterm Birth

·        At 27 weeks, 90% survive to discharge

·        Definitions:

o  Prematurity: < 37 = weeks Preterm, < 33 = weeks Very preterm

o  Birth weight (?relevance to Pacific Island Babies – usually heavier):

§  < 2.5 Kg: LBW

§  < 1.5 Kg: VLBW

§  < 1.0 Kg: Extremely low birth weight

·        Factors affecting prognosis:

o  Prenatal: Socio-economic, maternal smoking, infertility

o  Antenatal: multiple birth, IURG, maternal illness, smoking, steroids before delivery

o  Birth: time of transfer, method of delivery, APGAR, resuscitation

o  Postnatal:

§  Size of NICU, surfactant, breast feeding 

§  Hypoxic-Ischaemic Encephalopathy (HIE): ¯O2 delivery to brain ® becomes oedematous over next 24 – 48 hours 

·        Assessment of outcome: lots of problems with cohort studies: which population, admission, length of follow-up, what‟s measured, etc

·        Issues for mothers of NICU babies:

o  How they perceive health workers

o  Postnatal Depression

o  Visiting family commitments

o  Breast feeding: often expressing

Complications of Preterm Birth

·        Anaemia:

o  Miss out on the „iron loading‟ that happens through 3^rd trimester

o  Haemorrhage: feto-maternal, twin to twin, placental, cephalhaematoma, etc

o  Haemolysis: Rhesus disease, ABO incompatibility, spherocytosis, G6PD deficiency

o  Infection: CMV, rubella, septicaemia, UTI

o  Bleeding disorder: haemorrhagic disease of the new born

·        Respiratory Distress Syndrome:

o  =Hyaline Membrane Disease 

o  Inversely proportional to gestational age and birth weight, also diabetic mothers, asphyxia, cold stress, etc 

o  Surfactant deficiency ® alveolar collapse ® haemorrhage/protein leaking ® hyaline membrane

o  Signs: indrawing and expiratory grunt

o  CXR: ground glass appearance with air bronchogram.

·        Broncho-Pulmonary Dysplasia (BPD):

o  Follows ventilation for respiratory distress and O2 toxicity

o  Histology: necrotising bronchiolitis and alveolar fibrosis

o  Mortality 40%

o  Long term: airways obstruction, airways hyper-reactivity and hyper-inflation

o  CXR: patchy collapse and fibrosis with areas of cystic change and over-distension 

·        Intraventricular Haemorrhage (IVH): small haemorrhages into the germinal layer lining the lateral ventricles with hypoxia. May ® hydrocephalus. Most have no serious long term sequalae

·        Parenchymal Haemorrhage:

o  Into brain, not IVH

o  Incidence 1 – 2 % of preterms

o  Most are unilateral

o  Outcome depends on site

o  Varies from nil to severe hemiplegia

·        Periventricular Leukomalacia:

o  Incidence 4% of preterms

o  ?Associated with maternal infection

o   Frontal, usually watershed lesion 

o   Cysts long term ® spastic diplegia (legs worse than arm) 

·        Retinopathy of Prematurity: Abnormal vascularisation of retina following exposure to high O2 concentrations. Screen all babies < 31 weeks or 1500 g

·        Necrotising Enterocolitis:

o   During first 3 weeks (up to 3 months in VLBW infants).  Rare in term babies

o   Aetiology uncertain:

§  Hypoxic damage to bowel wall (?umbilical catheterisation, apnoeic spells, septicaemia)

§  Colonisation with certain bacteria: Clostridium perfringnes, E Coli, S Epidermidis, Rotavirus 

§  Necrotic segment of intestine with Pneumatosis Intestinalis („string of pearls‟ sign on X-ray plus portal gas seen in liver) ® perforation, sepsis, etc

o   Presentation: sepsis, bloody stools, bile stained vomiting

o   Pathogenesis:

§  Necrotising inflammation of the small and large intestine 

§  Mucosal oedema ® necrosis ® gangrene, perforation, peritonitis

o   Sequalae: malabsorption, strictures, short bowel syndrome 

·        Skin easily irritated (eg alcohol, tape, drips) ® long term scars

·        Also:

o   Jaundice more common

o   Hypoglycaemia more common

o   Failure of closure of patent ductus (give anti-PGs, eg endomethacin)

·        Problems associated with Intrauterine Growth Retardation:

o   Immediate:

§  Hypoglycaemia (see Hypoglycaemia of the New Born) 

§  Polycythaemia (eg due to placental insufficiency) ® heart failure (due to ­viscosity), pulmonary hypertension, NEC. Treat with exchange transfusion (eg or saline) ® ¯Hb 

§  Hypocalcaemia (test ALP)

§  Jaundice

§  Plus others (eg Cerebral Palsy)