Physiology of Pregnancy Flashcards
What is the role of the placenta?
To produce hormones in order to maintain pregnancy.
The driving force behind maternal adaptations.
What is the role of HCG?
Signals the corpus luteum to continue secreting progesterone.
What is the role of placental villi?
Project into the uterine wall, providing anchorage and increasing contact between the uterus and the placenta, allowing for a greater rate of nutrient/waste exchange.
What plays the role of the foetal lungs?
The placenta.
What factors facilitate the supply of foetal oxygen?
Foetal haemoglobin (increased O2 capacity)
Increased haemoglobin in foetal blood
Bohr effect
How does the Bohr effect impact foetal oxygenation?
Hb can carry more O2 due to a low PCO2.
How do electrolytes cross the placenta?
With water during osmosis.
Name 2 drugs to avoid in pregnancy due to their teratogenicity?
Carbamazepine
Tetracyclines
What is the role of human placental lactogen (HPL)?
A growth hormone, causing increased formation of protein tissue.
Reduces insulin sensitivity of mother - allowing energy to reach the foetus.
At around which week does HPL begin to be produced?
Week 5.
What is the role of progesterone in pregnancy?
Decreases uterine contractility
Enlarges breasts for lactation
What is the the role of oestrogen in pregnancy?
Enlarges uterus
Enlarges breasts
Relaxation of ligaments
How often should HCG levels double in early pregnancy?
Every 48 hours.
What symptoms are associated with increasing levels of HCG?
Nausea and vomiting
What does a slow rising/static HCG level indicate?
Ectopic pregnancy
What does a falling HCG level indicate?
Miscarriage or an unviable pregnancy.
What do extremely high levels of HCG suggest?
Multiple pregnancy
Molar pregnancy
At which gestation does HCG levels begin to fall again?
12-14 weeks.
What change is seen in cardiac output during pregnancy?
Increase by 30-50%.
What change is seen to BP in pregnancy?
Drops in 2nd trimester by around 15mmHg, with a rise in the 3rd trimester expected.
What is anaemia defined as in the first trimester?
<110g/L of Hb
What is anaemia defined as in the second and third trimesters?
<105g/L of Hb
What is a normal haemoglobin level in a healthy individual?
120-160g/L of Hb
Why do Hb levels drop in pregnancy?
Increased plasma volume.
What respiratory changes are seen in pregnancy?
Increased respiratory rate
Increased tidal and minute volume
Slight decrease in PCO2
Are vital capacity and PO2 changed by pregnancy?
No
Are GFR and plasma affected by pregnancy?
Yes, they increase by 30-50%.
Why does urinary frequency increase during pregnancy?
Increased uterine pressure
Increased urinary formation (minimal)
Is pregnancy a hypercoagulable state?
Yes
This is advantageous in preventing haemorrhage, however there is increased risk of thromboembolism.
What supplementation is advised in pregnancy?
Folic acid Vitamin D High protein diet High energy intake Iron supplements (if needed) Vitamin B
What rises to increase uterine excitability towards the end of pregnancy?
Oestrogen : Progesterone ratio
The greater the amount of oestrogen present, the greater the rate of uterine contraction.
What is the role of oxytocin?
Increase contractions and uterine excitability.
Where is oxytocin produced?
The posterior pituitary of the mother.
What are Braxton-Hicks contractions?
Tightenings of the uterus felt towards the end of pregnancy.
These are not labour.
Are Braxton-Hicks contractions regular and painful?
No, they are neither of these things.
What is the first stage of labour?
Dilatation of the cervix (can take 8-24 hours).
What is the second stage of labour?
Passage of the foetus through the birth canal (can take a few hours).
What is the third stage of labour?
Expulsion of the placenta.
What role does oestrogen play in breast development?
Maturation and growth of the ductile system of the breasts, allowing for milk production.
What role does progesterone play in breast development?
Allows for development of the lobule-alveolar system.
Which hormone stimulates milk production?
Prolactin
What is the antibody-rich milk produced in the first few days following birth called?
Colostrum
