What change occurs to the maternal blood volume during pregnancy? Why?
Blood volume increases ~ 50%
- To supply growing foetus
- To supply overactive kidneys
- In anticipation of ~500 ml blood loss @ birth
What change occurs to the maternal cardiac output during pregnancy? Why does this occur?
Increases ~ 40%
- Due to increase in blood volume = increased stroke volume
- Slight increase in heart rate
What is the average heart rate of the mother during pregnancy?
~ 80-90 bpm
What changes to the maternal heart may you notice on auscultation/palpation?
- Upwards displacement
- Flow murmurs
What change occurs to maternal GFR during pregnancy, and how does this affect creatinine clearance?
- Increased GFR
- Increased creatinine clearance
What causes pregnant women to be at increased risk of developing hydroureter and UTI’s?
- Gravid uterus may compress ureter’s against pelvic brim
- Progesterone causes relaxation of smooth muscle in walls of ureters and bladder, causing urinary stasis
What affect does progesterone have on the maternal respiratory system? Why does it do this?
Progesterone drives hyperventilation:
- Increases excretion of CO2
- Maintains CO2 gradient from foetus to mother
Why are pregnant women at risk of developing respiratory alkalosis?
Progesterone causes hyperventilation
What change occurs to the maternal O2 consumption during pregnancy?
Increases ~ 15%
What change occurs to the maternal tidal volume during pregnancy? How does this not affect the vital capacity?
Increases ~ 40 %
- Doesn’t affect vital capacity as the functional residual capacity decreases during pregnancy
What change occurs to the maternal respiratory rate during pregnancy?
What change occurs to the amount of insulin released into the maternal bloodstream after a meal, particularly in early pregnancy? Why does this occur?
Increased insulin release
= Increased uptake of glucose into body cells
= More energy stored in body, to be used by foetus in later stages of pregnancy
Why do levels of free fatty acids, ketones and triglycerides rise in the maternal serum as pregnancy progesses?
- hPL increases maternal resistance to insulin, allowing increased glucose availability to foetus
- This forces mother to switch to gluconeogenesis and lipolysis, to generate alternative fuels for her body cells
Why do levels of Calcitriol rise in the mother during pregnancy?
- Increase Ca2+ absorption from the gut
- Used for foetal growth and bone development
What change occurs to the appendix during pregnancy?
Moves up towards RUQ due to displacement by the uterus
Why is venous engorgement and distention associated with late pregnancy? What problems may this cause?
- Gravid uterus compresses IVC
- Progesterone causes venodilation
- Varicose veins
Why are pregnant women said to be in a ‘hypercoagulable state’?
- Increased fibrinogen and clotting factors
- Decreased fibrinolysis
- Stasis (IVC compression + venodilation)
Why do pregnant women suffer physiological dilutional anaemia?
- Plasma volume increases ~ 50%
- Red blood cell number increases ~ 20/30%
= Diluted blood
List some foetal problems associated with gestational diabetes:
- Shoulder dystocia
- Brain damage due to reflex hypoglycaemia
- Newborn respiratory disorders
- Cardiac defects
- Neural tube defects
What are some problem associated with maternal anaemia?
- Foetal growth retardation
- Maternal mortality
What is the Barker hypothesis?
Decreased foetal growth may lead to chronic adult conditions such as DMII, CVD, hypertension etc.