Week 12

Question 1

What defines the embryonic period and the foetal period?

Answer 1

Embryonic period: first 10 weeks

Foetal period: last 30 weeks

Question 2

What are the two main factors that affect placental and thus foetal growth?

Answer 2

1. Pre-eclampsia (5-8%)
   - Lack of cytotrophoblast invasion and spiral artery remodelling
2. Placental insufficiency
   - The placenta does not develop properly
3. Placental abruption:
   - Part of the placenta comes of maternal uterine wall
   - Causes foetal and/or maternal haemorrhage and foetal asphyxia
4. Placental infarction:
   - Poor blood supply to part of the placenta
   - These regions become necrotic
5. Placenta previa:
   - Placenta is located over cervix
   - Requires c-section to avoid haemorrhage

Question 3

What percentage of babies born in Aus are preterm and IUGR?

Answer 3

• 8% of babies are born preterm (<37 weeks)
• 6% of babies are born with IUGR (<2.5kg)
• These babies have a much greater risk of perinatal death

Question 4

What are the complications of preterm birth and IUGR?

Answer 4

• Incomplete organ development: specifically,
  1. Lung:
• lack type I and II epithelial cells
• thick blood gas barrier
• lack surfactant
• low compliance
• poor liquid clearance
• Respiratory support can injure the lungs and cause bronchopulmonary dysplasia

2. Cardiovascular system:
   - In the foetus there is the DV which shunts blood away from the liver
   - The FO allows blood from right atrium to be passed straight into left atrium
   - The DA causes any blood from the pulmonary arch to be shunted into the aorta
   - These shunts mean only 5% of air goes to feotal lungs
3. Brain:
   - Even though in IUGR blood is redirected to the brain there is still increased risk of:
4. Neurological alterations
5. Motor and cognitive dysfunction
6. High rates of cerebral palsy

Question 5

How is lung injury reduced at birth?

Answer 5

• By using expiratory pressure during respiratory support

- This prevents the lungs from collapsing between breaths and means air remains in the lungs and reaches the alveoli

Question 6

How is brain injury reduced at birth?

Answer 6

• Sheep models show that using melatonin may reduce brain damage in IUGR babies