Perinatal adaptation

Question 1

What are some of the functions of the placenta?

Answer 1

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

Question 2

Umbilical cord connects foetus to the placenta. true/false?

Answer 2

True

Question 3

How many blood vessels are present in the umbilical cord?

Answer 3

Contains 3 blood vessels – one vein which carries oxygenated blood to the baby, 2 arteries which carry deoxygenated blood back to the placenta.

Question 4

What is the use of shunts in the foetal circulation?

Answer 4

Small passages that direct blood that needs to be oxygenated.

The purpose of these shunts is to bypass the lungs and liver. That’s because these organs will not work fully until after birth.

Question 5

How many shunts are in the foetal circulation and what are they?

Answer 5

Three Shunts
- Ductus venosus
- Foramen ovale
- Ductus arteriosus

Question 6

As gestational age increases, what is produced by the type 2 pneumocytes (alveolar cells)?

Answer 6

Surfactant to lower surface tension in lungs.

Question 7

What is the function of placental in cardiorespiratory adaption?

Answer 7

Switch from placental gas exchange to air breathing
- Reabsorb lung fluid and establish air filled lung
- Adapt circulation for lung gas exchange

Question 8

What happens in the first seconds of the baby being born?

Answer 8

• Blue
• Starts to breathe
• Cries
• Gradually goes pink
• Cord flow stops then cord clamped and cut

Question 9

What causes duct constriction in foetus?

Answer 9

• Increased oxygen
• Decreased flow
• Decreased prostaglandins

Question 10

What occurs in the first few hours after child birth?

Answer 10

Thermoregulation
Glucose homeostasis
Nutrition

Question 11

Thermoregulation in utero (before birth)?

Answer 11

Mum responsible for thermoregulation

Lots of brown fat laid down between scapulae and around internal organs in 3rd trimester
- Less in growth restricted or preterm infants.

Question 12

Thermoregulation after birth?

Answer 12

Main source of heat production is non shivering thermogenesis
- Heat produced by breakdown of stored brown adipose tissue in response to catecholamines
- Not efficient in the first 12 hours of life

Peripheral vasoconstriction
No shivering

Newborn babies need help with maintaining temperature

Question 13

Glucose homeostasis in utero (before birth)?

Answer 13

In utero glucose comes via placenta in constant supply

Glycogen stores created in liver and muscle in preparation for birth

Question 14

Glucose homeostasis after birth?

Answer 14

Interruption of glucose supply from placenta

Very little oral intake of milk

Drop in insulin, increase in glucagon

Mobilisation of hepatic glycogen stores for gluconeogenesis

Ability to use ketones and lactate as brain fuel

Question 15

Nutrition after delivery?

Answer 15

In the first few minutes after birth babies will start the process of looking for nutrition

Gut prior to birth is sterile

As well as calories / lipids / proteins the baby needs to establish its gut microbiome

Birth canal, skin to skin contact, feeding all important in this

Breast milk has numerous factors which help establish a healthy microbiome

Medical interventions may hinder the process

Question 16

Breast feeding features?

Answer 16

Baby starts to suckle
- Rooting and Suck reflex

Feedback loop causes increase in supply. Controlled by hypothalamic stimulation resulting in supply and demand - more milk drank = more milk produced

Composition changes
- Colostrum (first secretion from mammary glands after giving birth).
- Foremilk and hindmilk

Question 17

What happens the next few days/weeks after birth?

Answer 17

Haematological changes
Jaundice
Weight loss / gain

Question 18

Haematological changes occurring in foetus after birth?

Answer 18

Foetal haemoglobin
- Becomes disadvantageous
- Increase in 2,3 DPG shifts curve to right

Haematopoiesis moves to bone marrow

Adult Hb synthesised more slowly than Fetal Hb broken down
- Physiological anaemia
- Nadir (lowest reading) at 8-10 weeks

Question 19

Liver changes occurring in foetus after birth?

Answer 19

Enzyme pathways present but immature

Physiological Jaundice
- Breakdown of fetal haemoglobin
- Conjugating pathways immature
- Rise in circulating unconjugated bilirubin
- Generally not harmful unless very high levels
- Risk of Kernicterus (bilirubin-induced brain dysfunction).

Early or prolonged jaundice may be pathological (appearing within 24hr after birth or still being present after 14 days of life).

Question 20

What is peristent pulmonary hypertension of the newborn (PPHN)?

Answer 20

Under certain circumstances the circulation does not transition effectively to the postnatal configuration. So foetal circulation remains and is unable to adapt to outside environment.

This generally happens when the pulmonary resistance does not drop for some reason. This can be because of hypoxia, acidosis, cold stress, lung disease, sepsis or in some cases idiopathic.

One of the most common situations where we see this problem is in babies who have had an asphyxial insult during delivery. They develop acidosis, often aspiration pneumonia, hypoxia and the pulmonary vascular resistance stays high.

Question 21

Management of PPHN?

Answer 21

Ventilation

Oxygen

Nitric oxide (an even more potent lung vasodilator than oxygen and the aim is to relax the pulmonary arterioles to allow more blood to flow to the lungs)
Sedation

Inotropes

ECLS

Main aim is to keep baby oxygenated, carried out through ventilation.

Question 22

What are some risk factors that can cause adaptation problems?

Answer 22

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