Physiology at Birth

Question 1

What 3 major changes do babies experience at birth?

Answer 1

1. Oxygenation
2. Circulation
3. Nutrition

Question 2

Oxygenation

Answer 2

• No more placenta
• Neonate begins to breathe within seconds and normalizes respirations in less than 1 min
• Breathing initiated by sudden exposure to world and slightly asphyxiated state (placental separation or cord compression can interfere wtih this)
• Neonates can survive as long as 10 minutes without breathing but 8-10 min = brain damage
• Lots of negative intrapleural pressure is required to open collapsed alveoli = big cries
• Surfactant decreases surface tension of alveoli and helps open
• Easier to breathe if past age of surfactant

Question 3

Circulation

Answer 3

• No more placenta
• Blood needs to go to lungs and liver
• Decreased pulmonary vascular resistance: reduces resistance to blood flow through lungs
• Increased systemic vascular resistance: increased aortic and L atrium and L ventricle pressure
• Closure of foramen ovale bc pressure change in atria
• Closure of ductus arteriosus bc increased O2 of blood
• Closure of ductus venosus

Question 4

Nutrition

Answer 4

• No more placenta
• Initially uses its own stored glucose but only lasts a few hours
• Liver is immature so not effective at producing glucose
• Stored fats and proteins for a few days
• See weight loss up to 20%
• Nursing considerations: monitor food, weights, Is and Os, should be back up to birth weight by 2 weeks