Physiology in Pregnancy

Question 1

What changes happen to a women’s breasts during pregnancy?

Answer 1

• Increased size and vascularity (warm, tense and tender)
• Increased pigmentation of the areola and nipple
• Secondary areola appears
• Montgomery tubercules appear on the areola
• Colostrum like fluid can be expressed from the end of the 3rd month

Question 2

What happens to the cardiovascular system during pregnancy?

Answer 2

• Increased circulating blood volume
• Systemic vascular resistance falls
• Increased blood flow
• Increased cardiac output (due to increased stroke volume)
• Increased heart rate
• 25% reduction of cardiac output in the supine position
• Increased oxygen consumption

Question 3

What cardiovascular changes occur during labour?

Answer 3

• Autotransfusion of contractions
• Pain: increased catecholamines
• CO increases by 10% in labour and by 80% in first post delivery hour

Question 4

What cardiovascular changes occur after birth?

Answer 4

• Returns to normal after 3 months
• Blood volume decreases by 10% 3 days post delivery
• BP initially falls then increases again 3-7 days later
• SVR increases over first 2 weeks to 30% above delivery levels
• HR returns to normal over 2 weeks
• CO begins to fall after the first hour and then over the next 24 weeks

Question 5

What happens to the respiratory system during pregnancy?

Answer 5

• 20% increase in oxygen demand
• 40-50% increase in minute ventilation
• Increased RR and increased tidal rate
• Decreased functional residual capacity
• PEFR and FEV1 are unchanged
• Decreased PCO2

Question 6

What happens to the renal system during pregnancy?

Answer 6

• Massive dilatation of the urinary collecting system
• Increased renal plasma flow (60-80% by end of 2nd trimester)
• Increased GFR and creatinine clearance
• Protein excretion increases
• Microscopic haematuria may be present and 80% develop oedema
• Glycosuria is common
• Urate levels increase with gestation
• Urea and creatinine levels decrease

Question 7

What haematological changes happen during pregnancy?

Answer 7

• Plasma volume increases
• Hg, Hcrit and RCC decrease
• No change in MCV or MCHC
• Decreased platelet count
• 2-3 fold increase in requirement for iron
• 10-20 increase in folate requirements
• WCC increases
• Hypercoagulable