Foetal Adaption at birth Flashcards
What is the role of the placenta?
foetal homeostasis gas exchange nutrient transport to foetus whole product transport from foetus acid base balance hormone production transport of IgG
What % of foetal circulation goes through the lungs?
7%
What are the 3 shunts that close after a baby is born?
ductus venosus
foramen ovale
ductus arteriosus
What does the ductus venosus become?
ligamentum teres
What does the foramen ovale become?
closes completely or persists as patent foramen ovale
What does the ductus arteriosus become?
ligamentum arteriosus
How does the pulmonary vascular resistance change at birth?
decreases
How does the systemic vascular resistance change at birth?
increases
How does oxygen tension change at birth?
increases
How do the levels of circulating prostaglandins change at birth?
decrease
What is persistant pulmonary hypertension of the newborn?
marked pulmonary hypertension that causes hyperaemia secondary to right->left shunting of blood at the foramen ovale and ductus arterious
What causes persistant pulmonary hypertension of the newborn?
failure of normal circulation transition due to patent foramen ovale - they have no mechanism to close it
How is persistant pulmonary hypertension managed?
ventilation nitric oxide sedation inotrops ECCs
How does the babies body prepare for birth in the 3rd trimester?
surfacant production
accumulation of glycogen - liver, muscle, heart
accumulation of brown fat - between the scapulae and around internal organs
swallowing amniotic fluid
How does the babies body prepare for birth during labour?
increases catecholamines and cortisol
synthesis of lung fluid stops
vaginal delivery squeezes lungs
How do babies perform heat loss?
radiation
conduction
convection
evaporation
How do babies gain heat?
non shivering thermogenesis
What is non shivering thermogenesis?
heat is produced by the breakdown of stored brown adipose tissue in response to catecholamines
When does non shivering thermogenesis start?
AFTER 12 HOURS OF LIFE
Why does non shivering thermogenesis not happen in the first 12 hours of life?
low BMR
high surfacea area:body mass ratio
low brown adipose tissue
What 3 “hypos” are linked?
hypthermia
hypoxia
hypoglycaemia
Before the non shivering thermogenesis kicks in, how should you keep a baby warm?
keep them dry - they are born wet
give them a hat and a blanket
heated matress
How does glucose homeostasis change at birth?
increase in glycogen - mobilisation of these stores for gluconeogenesis
drop in insulin
What do babies use as brain fuel?
ketones
What are the 3 ways a baby can develop hypoglycaemia?
unwell/hypothermic -> increased energy demands
small/premature -> low glycogen stores
maternal diabetes/hyperinsulism -> innappropriate insulin/glucagon ratio
What does oxytocin cause in relation to breast feeding?
milk ejection
What changes happen haematologically at birth?
2,3,BPG curve -> RIGHT
haematopoesis moves to the bone marrow
How is physiological anaemia caused?
adult Hb is synthesised slower than foetal Hb is broken down
When does physiological anaemia peak?
8-10 weeks
What causes physiological jaundice?
breakdown of foetal haemoglobin but the conjugating pathway is immature which causes a rise in circulating unconjugated bilirubin
When is jaundice pathological?
<24hours of age
When does jaundice become prolonged?
if term = 2 weeks
pre term = 3 weeks
What is the usual course of physiological jaundice?
starts day 2
peaks day 5
