Problems of Low Birthweight and Prematurity Flashcards
What’s the median UK birth weight at term?
3.48kg
Define ‘low birthweight’
<2.5kg
Define ‘very low birthweight’
<1.5kg
Define ‘extremely low birthweight’
<1kg
Define ‘prematurity’
Birth before 37 weeks gestation
Define ‘small for gestational age’
Birthweight that is below the 10th gentile for gestation
Define ‘foetal growth restriction’
Failure to achieve normal rate of foetal growth
What are genetic causes for a baby being small for gestational age?
Normal, Edwards syndrome (trisomy 18) or inherited disorders
What are acquired causes for a baby being small for gestational age?
Uteroplacental insufficiency, CMV, maternal smoking, maternal chronic illness, multiple pregnancies
How may small babies present?
Cold (increased SA:V), polycythemia (increased Hb in the blood due to foetal hypoxia), hypoglycaemia and increased risk of necrotising enterocolitis
According to Barker, what may low birth weight lead to in later life?
Increased risk of: diabetes, hypertension, coronary heart disease, stroke and chronic bronchitis
What is utero-placental insufficiency?
Failure of the syncytiotrophoblast to invade the high-resistance spiral arteries, leading to poor placental development and raised resistance in the placental vascular bed leading to poor foetal growth
Which structures are prioritised in the redistribution of blood flow in the hypoxic foetus?
Increased blood flow to the brain, heart and adrenals. Blood supply elsewhere is reduced.
What are the causes of spontaneous preterm labour (prematurity)?
Infection/ruptured membranes, cervical incompetence or polyhydramnios
Why is temperature control an issue for a premature baby?
Large SA:V ration with thin skin and less adipose tissue (and being wet at birth). Can’t shiver and have a poor metabolic reserve for thermatogenesis so incubators are needed to provide warmth.
What are the respiratory concerns for a premature baby?
There is structural immaturity with primitive alveolar development (susceptibility to oxygen toxicity) and there is surfactant deficiency and a lack of respiratory drive. All alongside an immature immune system.
Describe the structure of surfactant
Monolayer of phospholipid consisting of DPPC and PG thetas stabilised by surfactant protein B
What is respiratory distress syndrome?
Due to lack of surfactant in a premature baby leading to tachypnoea, recession and expiratory grunting
What is chronic lung disease of infancy?
Where a preterm baby becomes oxygen-dependent
How is respiratory distress syndrome prevented?
Antenatal steroid (to stimulate surfactant production), avoid intrauterine hypoxia, prophylactic surfactant treatment, keep warm and avoid acidosis
How is respiratory distress syndrome treated?
Surfactant and respiratory support
What cardiovascular concerns may there be in a premature baby?
Persistent pulmonary hypertension of the newborn (PPHN), failure to maintain BP and patent ductus arteriosus
Which two infections are most likely to occur in the first 48 hours of life in a premature baby?
Group B streptococcus or E. Coli
Which infections are most likely to occur 48 hours after birth in a premature baby?
Hospital-acquired infections e.g. coagulase negative staphylococci or gram negative organisms which colonise the intestine
Why are premature babies more susceptible to infections?
Full-term baby has transplacental transmission of IgG in the 3rd trimester, IgA from breast milk (in colostrum). Pre-term infants are nursed in bacteriologically hostile environments so don’t develop ordinary gut microflora.
What are the neurological concerns for a pre-term baby?
Susceptibility to periventricular haemorrhage, risk of periventricular leukomalacia (ischaemia of periventricular white matter) and there is incomplete neuronal migration and room for further development with growth.
What are potential long-term complications of prematurity?
Cerebral palsy in 10% of those less than 1.5kg, cognitive and behavioural problems, sensory impairment, chronic lung disease of prematurity, retinopathy of prematurity
What is necrotising enterocolitis?
An acute bacterial invasion, inflammation and necrosis of the owl with gas formation in the bowel wall (pneumotosis)
What are the risk factors for necrotising enterocolitis?
Prematurity, hypoxia, infection and enteral feeding
What is the clinical presentation of necrotising enterocolitis?
Abdominal distention, tenderness, discolouration, colour in stools and general collapse
