Perinatal Adaptation

Question 1

List functions of the placenta

Answer 1

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

Question 2

What are the 3 shunts present in the foetal circulation?

Answer 2

Ductus venosus (eft umbilical vein blood flow to IVC)
Foramen ovale (oxygenated blood from RA to LA)
Ductus arteriosus (blood from RV to bypass lungs)

Question 3

Which foetal shunt allows oxygenated blood from the placenta to bypass the liver?

Answer 3

Ductus venosus

Question 4

List the stages of embryological development of the fetal lungs

Answer 4

Embryonic
Pseudoglandular
Cannalicular 
Saccular
Alveolar

Question 5

From what point in gestation, do babies start to produce surfactant?

Answer 5

24 weeks

Question 6

Which vessel carries oxygenated blood from the placenta to the foetus?

Answer 6

Umbilical vein via ductus venosus (liver) and IVC

Question 7

Once oxygenated blood reaches the right atrium, where can it go?

Answer 7

To right ventricle and pulmonary artery

To left atrium via foramen ovale (majority)

Question 8

Once oxygenated blood reaches the pulmonary artery, where can it go?

Answer 8

To lungs (7%)
To aorta via ductus arteriosus

Question 9

List ways a foetus prepares for birth

Answer 9

Surfactant production
Accumulation of glycogen
Accumulation of brown fat
Accumulation of subcutaneous fat
Swallowing amniotic fluid

Question 10

List physiological adaptions to the fetus during labour

Answer 10

Increase catecholamines/ cortisol
Synthesis of lung fluid stops
Vaginal delivery squeezes lungs

Question 11

Oxygen is a potent vasoconstrictor/ vasodilator of the lungs and is a potent vasoconstrictor/ vasodilator of vascular smooth muscle

Answer 11

Vasodilator

Vasoconstrictor

Question 12

List circulatory changes that occur in the fetus at birth

Answer 12

Pulmonary vascular resistance drops

Systemic vascular resistance increases

Question 13

Why do ducts constrict at birth?

Answer 13

Oxygen tension increases

Circulating prostaglandins reduce

Question 14

What does the ductus venosus become in circulatory transition?

Answer 14

Ligamentum teres

Question 15

What does the ductus arteriosus become in circulatory transition?

Answer 15

Ligamentum arteriosus

Persistant ductus arteriosus

Question 16

What does the foramen ovale become in circulatory transition?

Answer 16

Physiological closing

Patent foramen ovale (10%)

Question 17

List some causes of failed cardiorespiratory adaptation in a newborn

Answer 17

Cold stress
Prematurity
Meconium aspiration
Hypoxia

Question 18

What is persistent pulmonary hypertension of the newborn?

Answer 18

Resistance to lung blood flow remains high and foramen ovale persists, causing deoxygenated blood to flow to systemic circulation

Question 19

Outline management of persistent pulmonary hypertension of the newborn

Answer 19

Ventilation
Oxygen
Nitric oxide (lung vasodilator)
Sedation
Ionotropes
Extra-corporeal life support (ECLS)

Question 20

Why do babies lose heat quickly when they are born?

Answer 20

Large surface area

Wet when born

Question 21

List the four main methods of heat loss that can occur in the fetus

Answer 21

Evaporation
Conduction
Convection
Radiation

Question 22

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

Answer 22

Non-shivering thermogenesis

Mobilise brown fat stores in response to catecholamines

Question 23

State another way that babies thermoregulate

Answer 23

Peripheral vasoconstriction

Question 24

Why are small for dates or preterm babies more predisposed to hypothermia?

Answer 24

Low stores of brown fat
Little subcutaneous fat
Larger surface area: volume ratio

Question 25

How does glucose homeostasis change at birth?

Answer 25

Interruption of glucose supply from placenta leading to reduced insulin, increased glycogen for gluconeogenesis

Question 26

Why are small for dates or preterm babies more predisposed to hyperinsulinaemia?

Answer 26

Low glycogen stores leading to an inappropriate ratio of glycogen to insulin

Question 27

Give an example of a drug that increases the risk of neonatal hypoglycaemia

Answer 27

Labetalol for maternal hypertension

Question 28

What reflex helps the baby during breastfeeding?

Answer 28

Rooting and sucking reflex

Question 29

What harmone stimulates milk ejection from the breast following sucking? Where is it released from?

Answer 29

Oxytocin

Posterior pituitary

Question 30

What harmone stimulates milk production from the breast following sucking? Where is it released from?

Answer 30

Prolactin

Anterior pituitary

Question 31

What is colostrum?

Answer 31

Yellowish breastmilk that is produced in the first few days after baby’s birth that is rich in nutrients and antibodies

Question 32

What is foremilk?

Answer 32

Milk which is first drawn during feeding, generally thin and lower in fat

Question 33

What is hindmilk?

Answer 33

Milk which follows foremilk during feeding, richer in fat content and is high in calories

Question 34

In what direction does the haemoglobin dissociation curve shift from fetal to adult haemoglobin?

Answer 34

To the right

Increase in 2,3 DPG (increase oxygen affinity)

Question 35

Fetal haemoglobin is made in the liver before birth. Where does production of haemoglobin shift to after birth?

Answer 35

Bone marrow

Question 36

When is the lowest levels of haemoglobin in the fetus? What is the fetus at risk of?

Answer 36

8-10 weeks

Physiological anaemia

Question 37

When is jaundice in a newborn physiological?

Answer 37

When it occurs from 2 days to 2 weeks

Anything before or after this is pathological

Question 38

Why does physiological jaundice occur?

Answer 38

Liver enzyme pathways are present but immature

Question 39

List risk factors for adaptation problems

Answer 39

Hypoxia/ asphyxia during delivery
Small or large babies
Premature babies
Some maternal illness and medications
Ill babies e.g. sepsis, congenital anomalies