Pregnancy physiology

Question 1

Mechanical changes in pregnancy

Answer 1

• Increased weight gain, increased blood volume, enlarged foetus
• Altered centre of gravity → increased curvature of spine to prevent falling (more prone to back pain)
• Increased tissue pliability and extensibility
• Increased load on hip joints (x2.8)

Question 2

Metabolic changes during pregnancy

Answer 2

• Increased BMR (adapted to increased needs from foetus)
• Decreased insulin sensitivity due to human placental lactose (works against insulin(
• Increased maternal lipid storage

Question 3

Fatigue in pregnancy

Answer 3

• Pronounced in first trimester due to hormonal changes
• Evens out in second trimester
  
  • Returns in third trimester due to difficulty sleeping and advanced pregnancy

Question 4

Heartburn/ reflux in pregnancy

Answer 4

• Slower passage of food within GI tract and delayed gastric emptying
• Increased transient relaxation of LOS (GI tract)
• Enlarged uterus puts pressure on GI tract → worsens gastric emptying

Question 5

Why is general anaesthetic contraindicated in pregnancy

Answer 5

• Higher risk of aspiration due to increased relaxation of LOS
• Only regional anaesthetic (spinal and epidural)

Question 6

Peripheral oedema in pregnancy

Answer 6

• Physiological sodium and water retention and decreased excretion of sodium and water
• Increased blood volume, decreased venous return (compression of IVC)
• All leads to signs of peripheral oedema

Question 7

Breast changes in pregnancy

Answer 7

• Increase in size, vascularity → becomes hot and swollen
• Increased pigmentation of areola and nipples
• Appearance of Montgomery Tubercles
• Secretion of colostrum like fluid at end of 3rd month

Question 8

Thyroid changes in pregnancy

Answer 8

• Increased production of thyroid binding globulin bu liver
• Increased levels of total thyroxine
• Same level of free T3 and T4
• Relative iodine deficiency
  
  • Increased iodine demand from fetoplacental unit
  • Doubled urinary excretion, decreased tubular reabsorption of iodine
  • Hypertrophy of thyroid gland to increase iodine uptake

Question 9

Haematological changes in pregnancy

Answer 9

• Increased circulating volume, RBC mass → physiological anaemia
• Increase in plasma volume
• Decreased platelet count
• Increase in iron demand → iron deficiency
• Increase in folate demand
• Overall increase in WCC and neutrophil
• Hypercoagulable state
• All changes occur from early pregnancy to 6 weeks after pregnancy

Question 10

Renal changes in pregnancy

Answer 10

• Dilatation of urinary collection system
• Physiological hydronephrosis
• Increased renal plasma flow → decreased vascular resistance and increased circulating volume
• Increased GFR → lowers levels of urea and creatinine
• Increased excretion of protein
• Increased secretion of renin, vitamin D and erythropoietin
• Microscopic haematuria
• Glycosuria
• Increased prevalence of UTI’s
• Worsening underlying renal disease

Question 11

Lab values

Answer 11

• UP: WCC, ESR, 24 hour protein, alkaline phosphatase, d-dimer
• Down: haemoglobin, urea, creatinine, urate, albumin, total protein
• No change: CRP, bile acids
• Down/ no change: platelets, AST/ALT/ GGT