Physiology in Pregnancy

Question 1

what are the general changes in pregnancy? (7)

Answer 1

• weight gain
• fatigue- esp in early pregnancy
• breast changes
  
  • increase in size and vascularity
  • increase in pigmentation of nipple and areola
• general state of immunosuppression
• 80% of women develop oedema by third trimester
• indigestion/ reflux
  
  • sphincter at top of stomach relaxes
• thyroid enlarges
  
  • iodine deficient

Question 2

why do 80% of women develop oedema by 3rd trimester?

Answer 2

due to reduced ability to excrete sodium

Question 3

outline the CVS changes that occur with pregnancy

Answer 3

• increase in circulating blood volume (50-70% that of non-pregnant)
  
  • increased blood flow
• increase in HR, SV and CO
• reduced SVR
• increased O2 consumption
• BP reduces in 2nd trimerster but then increases again in 3rd

Question 4

what is a common cardiac complaint of pregnant women?

Answer 4

palpitations

• due to increased HR and CO

Question 5

what happens when a pregnant woman is lying supine?

Answer 5

25% reduction in CO due to the foetus pressing the IVC

Question 6

outline the intra-partum CVS changes

Answer 6

• pain= increased catecholamines
• CO increases by 10% during labour, and by 80% in hour post-partum

Question 7

outline the post-partum CVS changes

Answer 7

• generally, return to normal by 3 months
• Blood volume decreases by 10% within 3 days
• BP initially falls but then rises again in 3-7days
• HR goes back to normal within 2 weeks post-partum
• SVR increases in 1st 2 weeks
• CO goes back to normal over 24weeks post-partum

Question 8

outline the respiratory changes

Answer 8

• 20% increase in oxygen consumption
• increase in RR + Tidal Volume
• reduced functional residual capacity
• reduced PCO2
• increase in ventilation
• PEFR + FEV1 remain unchanged

Question 9

outline the changes in the renal system in pregnancy

Answer 9

• massive dilation of collecting duct system
• increase in renal plasma flow
• increase in GFR & Creatinine clearance by 50%
• reduced creatinine and urea
• increased protein excretion
• microscopic haematuria may be present
• glycosuria common
• urate increases with increasing gestation

Question 10

with relation to changes in the urinary system during pregnancy, what may be seen in the 3rd trimester?

Answer 10

• increased urinary stasis
• hydronephrosis is physiological in 3rd trimester
• however, can go on to cause pyelonephritis
• this can in turn lead to preterm labour
• so needs to be treated promptly

Question 11

outline the haematological changes in pregnancy

Answer 11

• increase in plasma volume
• reduced Hb (dilution)
• reduced platelets (dilution)
• hypercoabulable state
• increased WCC
• 2-3 fold increase in folate requirements

Question 12

outline the GI changes during pregnancy

Answer 12

• reduced oesophageal peristalsis
• reduced gastric motility
  
  • due to an increase in progesterone and reduction in motilin
• gastric emptying slows

Question 13

outline whether the following lab values would be increased, unchanged or reduced in pregnancy:

• Hb
• WCC
• Platelets
• CRP
• ESR
• Urea
• Creatinine
• Urate
• Total protein
• Albumin
• AST/ALT/GGT
• Alk Phos
• Bile Acids
• D-Dimer

Answer 13

• Hb ↓
• WCC ↑
• Platelets ↓
• CRP - unchanged
• ESR ↑
• Urea ↓
• Creatinine ↓
• Urate ↓ - BUT ↑ with gestation
• Total protein ↓
• Albumin ↓
• AST/ALT/GGT- unchanged
• Alk Phos ↑↑
• Bile Acids - unchanged
• D-Dimer ↑

Question 14

why is ESR raised in pregnancy?

Answer 14

body fighting off “foreign body”

Question 15

why is Alk Phos raised in pregnancy?

Answer 15

placenta produces it