Perinatal adaptation Flashcards
What are some of the functions of the placenta?
- Foetal homeostasis
- Gas exchange
- Nutrient transport to fetus
- Waste product transport from fetus
- Acid base balance
- Hormone production
- Transport of IgG
Umbilical cord connects foetus to the placenta. true/false?
True
How many blood vessels are present in the umbilical cord?
Contains 3 blood vessels – one vein which carries oxygenated blood to the baby, 2 arteries which carry deoxygenated blood back to the placenta.
What is the use of shunts in the foetal circulation?
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.
How many shunts are in the foetal circulation and what are they?
Three Shunts
- Ductus venosus
- Foramen ovale
- Ductus arteriosus
As gestational age increases, what is produced by the type 2 pneumocytes (alveolar cells)?
Surfactant to lower surface tension in lungs.
What is the function of placental in cardiorespiratory adaption?
Switch from placental gas exchange to air breathing
- Reabsorb lung fluid and establish air filled lung
- Adapt circulation for lung gas exchange
What happens in the first seconds of the baby being born?
- Blue
- Starts to breathe
- Cries
- Gradually goes pink
- Cord flow stops then cord clamped and cut
What causes duct constriction in foetus?
- Increased oxygen
- Decreased flow
- Decreased prostaglandins
What occurs in the first few hours after child birth?
Thermoregulation
Glucose homeostasis
Nutrition
Thermoregulation in utero (before birth)?
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.
Thermoregulation after birth?
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
Glucose homeostasis in utero (before birth)?
In utero glucose comes via placenta in constant supply
Glycogen stores created in liver and muscle in preparation for birth
Glucose homeostasis after birth?
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
Nutrition after delivery?
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
Breast feeding features?
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
What happens the next few days/weeks after birth?
Haematological changes
Jaundice
Weight loss / gain
Haematological changes occurring in foetus after birth?
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
Liver changes occurring in foetus after birth?
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).
What is peristent pulmonary hypertension of the newborn (PPHN)?
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.
Management of PPHN?
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.
What are some risk factors that can cause adaptation problems?
- 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
