Problems of Low Birthweight and Prematurity

Question 1

What’s the median UK birth weight at term?

Answer 1

3.48kg

Question 2

Define ‘low birthweight’

Answer 2

<2.5kg

Question 3

Define ‘very low birthweight’

Answer 3

<1.5kg

Question 4

Define ‘extremely low birthweight’

Answer 4

<1kg

Question 5

Define ‘prematurity’

Answer 5

Birth before 37 weeks gestation

Question 6

Define ‘small for gestational age’

Answer 6

Birthweight that is below the 10th gentile for gestation

Question 7

Define ‘foetal growth restriction’

Answer 7

Failure to achieve normal rate of foetal growth

Question 8

What are genetic causes for a baby being small for gestational age?

Answer 8

Normal, Edwards syndrome (trisomy 18) or inherited disorders

Question 9

What are acquired causes for a baby being small for gestational age?

Answer 9

Uteroplacental insufficiency, CMV, maternal smoking, maternal chronic illness, multiple pregnancies

Question 10

How may small babies present?

Answer 10

Cold (increased SA:V), polycythemia (increased Hb in the blood due to foetal hypoxia), hypoglycaemia and increased risk of necrotising enterocolitis

Question 11

According to Barker, what may low birth weight lead to in later life?

Answer 11

Increased risk of: diabetes, hypertension, coronary heart disease, stroke and chronic bronchitis

Question 12

What is utero-placental insufficiency?

Answer 12

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

Question 13

Which structures are prioritised in the redistribution of blood flow in the hypoxic foetus?

Answer 13

Increased blood flow to the brain, heart and adrenals. Blood supply elsewhere is reduced.

Question 14

What are the causes of spontaneous preterm labour (prematurity)?

Answer 14

Infection/ruptured membranes, cervical incompetence or polyhydramnios

Question 15

Why is temperature control an issue for a premature baby?

Answer 15

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.

Question 16

What are the respiratory concerns for a premature baby?

Answer 16

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.

Question 17

Describe the structure of surfactant

Answer 17

Monolayer of phospholipid consisting of DPPC and PG thetas stabilised by surfactant protein B

Question 18

What is respiratory distress syndrome?

Answer 18

Due to lack of surfactant in a premature baby leading to tachypnoea, recession and expiratory grunting

Question 19

What is chronic lung disease of infancy?

Answer 19

Where a preterm baby becomes oxygen-dependent

Question 20

How is respiratory distress syndrome prevented?

Answer 20

Antenatal steroid (to stimulate surfactant production), avoid intrauterine hypoxia, prophylactic surfactant treatment, keep warm and avoid acidosis

Question 21

How is respiratory distress syndrome treated?

Answer 21

Surfactant and respiratory support

Question 22

What cardiovascular concerns may there be in a premature baby?

Answer 22

Persistent pulmonary hypertension of the newborn (PPHN), failure to maintain BP and patent ductus arteriosus

Question 23

Which two infections are most likely to occur in the first 48 hours of life in a premature baby?

Answer 23

Group B streptococcus or E. Coli

Question 24

Which infections are most likely to occur 48 hours after birth in a premature baby?

Answer 24

Hospital-acquired infections e.g. coagulase negative staphylococci or gram negative organisms which colonise the intestine

Question 25

Why are premature babies more susceptible to infections?

Answer 25

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.

Question 26

What are the neurological concerns for a pre-term baby?

Answer 26

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.

Question 27

What are potential long-term complications of prematurity?

Answer 27

Cerebral palsy in 10% of those less than 1.5kg, cognitive and behavioural problems, sensory impairment, chronic lung disease of prematurity, retinopathy of prematurity

Question 28

What is necrotising enterocolitis?

Answer 28

An acute bacterial invasion, inflammation and necrosis of the owl with gas formation in the bowel wall (pneumotosis)

Question 29

What are the risk factors for necrotising enterocolitis?

Answer 29

Prematurity, hypoxia, infection and enteral feeding

Question 30

What is the clinical presentation of necrotising enterocolitis?

Answer 30

Abdominal distention, tenderness, discolouration, colour in stools and general collapse