Perinatal Adaptation

Question 1

What are some placental functions?

Answer 1

Fetal homeostasis
Gas exchange
Nutrient transport to fetus
Waste product transport from fetus
Acid base balance
Hormone production
Transport of IgG

Question 2

What are the 3 fetal shunts?

Answer 2

Ductus venosus
Foramen ovale
Ductus arteriosus

Question 3

How does the fetus prepare for birth in the 3T?

Answer 3

Surfactant production
Accumulation of glycogen-liver, muscle, heart
Accumulation of brown fat- between scapulae and around internal organs
Accumulation of subcut fat
Swallowing amniotic fluid

Question 4

How does the fetus prepare for birth during labour and delivery?

Answer 4

Onset of labour- increased catecholamines/cortisol
Synthesis of lung fluid stops
In vaginal delivery- squeezes lungs

Question 5

What circulatory transition occurs at birth?

Answer 5

Pulmonary vascular resistance drops
Systemic vascular resistance rises
Oxygen tension rises
Circulating prostaglandins drop
Duct constricts
Foramen ovale closes

Question 6

What happens to the foramen ovale after birth?

Answer 6

Closes or persists as PFO (10%)

Question 7

What happens to the ductus arteriosus after birth?

Answer 7

Becomes ligamentum arteriosus

Persistent ductus arteriosus (causing persistent pulmonary HT)

Question 8

What happens to the ductus venosus after birth?

Answer 8

Becomes ligamentum teres

Question 9

How is PPHN managed?

Answer 9

Ventilation
Oxygen
Nitric oxide
Sedation
Inotropes
ECLS

Question 10

By what methods does heat loss occur?

Answer 10

Radiation
Convection
Evaporation
Conduction

Question 11

How is a baby adapted for thermoregulation?

Answer 11

Large SA

Wet when born

Question 12

What is the main source of heat production in the newborn?

Answer 12

Non shivering thermogenesis- heat produced by breakdown of stored brown adipose tissue in response to catecholamines, not efficient in first 12 hours

Question 13

What other methods of thermoregulation exist in the newborn?

Answer 13

Peripheral vasoconstriction

Babies need help to maintain temp

Question 14

Why may small for dates/PT babies suffer from hypothermia?

Answer 14

Low stores of brown fat
Little subcut fat
Larger SA:V

Question 15

How can hypothermia be avoided in the newborn?

Answer 15

Dry
Hat
Skin to skin
Blanket/clothes
Heated mattress
Incubator

Question 16

Describe glucose homeostasis in the newborn

Answer 16

Interruption of glucose supply from placenta
Very little oral intake of milk
Drop in insulin, increase in glycogen
Mobilisation of hepatic glycogen stores for gluconeogenesis
Ability to use ketones as brain fuel

Question 17

How does hypoglycaemia occur in the newborn?

Answer 17

Increased energy demands-unwell, hypothermia
Low glycogen stores- small, premature
Inappropriate insulin/glucagon ratio- maternal diabetes, hyperinsulinism
Some drugs

Question 18

What happens to fetal haemoglobin in the newborn?

Answer 18

Becomes disadvantageous

Increase in 2,3 DPG shifts curve to right

Question 19

Where does haematopoiesis move to in the newborn?

Answer 19

Bone marrow

Question 20

What can result from adult Hb being synthesised more slowly than fetal Hb breakdown?

Answer 20

Physiological anaemia

Nadir at 8-10 wks

Question 21

Why does physiological jaundice occur in the newborn?

Answer 21

Breakdown of fetal haemoglobin
Conjugating pathways immature
Rise in circulating unconjugated bilirubin
Generally not harmful unless very high levels

Question 22

What are some RFs for adaptation problems?

Answer 22

Hypoxia / asphyxia during delivery
Particularly small or large babies
Premature babies
Some maternal illnesses and medications
Ill babies – sepsis, congenital anomalies