Physiology in Pregnancy Flashcards
List some general changes to the body during pregnancy? [8]
- Increased lumbar curvature to compensate for the belly
- Fatigue
- Reflux due to loosening of GI sphincters > GORD
- Oedema
- Breast
- Thyroid (iodine used up so thyroid enlarges to compensate)
- General Immunosuppression
- Weight Gain
How does the breast change during pregnancy? [4]
- Bigger and more vascular (warm, tense & tender)
- Areola/nipple get darker & 2nd* areola appears
- Montgomery tubercules appear on areola
- Colostrum-like fluid from as early as 3rd
How does blood volume change during pregnancy?
Up to 50-70% more blood volume while pregnant
How does heart activity change during pregnancy? [2]
Why does CO increase so much during pregnancy?
SV and HR rise leading to a much higher CO. Most women have Sinus Tachycardia during pregnancy
SVR also drops significantly
Why does CO increase so much during pregnancy?
Because O2 consumption goes way up
How can changing position affect a pregnant woman’s CO?
Why is it important to understand how a pregnant woman’s CO decreases in supine position? [2]
If they lie supine the foetus presses on the IVC reducing venous return and so reducing CO.
Trying to do CPR and resuscitation on a pregnant woman is impossible if lying supine, you must move the uterus or lie then tilted.
Also never examine a pregnant woman supine, let them sit up or lie on the side
How does increased CO affect risk of heart problems? [1]
Increased CO means the heart muscle requires more O2. Thus there’s an increased risk of angina or MI
How does blood volume and pressure change during labour? [2]
How does CO change during labour?
When does the CV system return to normal after pregnancy?
How long does BP take to return to normal?
How long before HR returns to normal?
How long before CO returns to normal?
Every contraction pushes blood from uterus into systemic circulation (Autotransfusion).
This increases blood volume and BP so is dangerous, especially in people with existing BP problems or stenotic lesions
How does CO change durine labour?
Increases by 10% during labour and up to 80% in the first hr post-delivery.
Post-partum:
CV system are back to normal within 3 months
BP falls and increases again in the first 7 days but returns to pre-preg levels by 6wks
HR returns to normal in 2 weeks
CO increases by 80% in first hour post delivery then falls back to normal over 24 weeks
How do the lungs change during pregnancy? [2]
How do O2/CO2 levels change during pregnancy? Clinical implications? [2]
40-50% increase in ventilation with RR and tidal volume increasing. (to compensate for increases O2 demand)
But PEFR and FEV1 are unchanged
O2 rises and CO2 drops due to increased ventilation. So looks like compensated respiratory alkalosis on blood gases.
How does the renal system change structurally during pregnancy? [2]
It dramatically dilates (particularly on the right).
Both the ureters and kidneys dilate due to pressure from uterus and progesterone
How does function of the kidneys change in pregnancy? [3]
What happens to protein excretion - clinical significance?
Renal plasma flow goes up by 60-80% by end of trimester 2
- -> Increased GFR and Creatinine clearance
- -> Urea and Creatinine fall
Protein excretion goes up ergo 24hr urine protein rises and total protein/Albumin drop
Glycosuria is common
What happens to urate during pregnancy
What is uric acid level used for in pregnancy? [2]
Urate rises with gestation
A marker of pre-eclampsia
It also increases with gestation so the level can be predicted based on gestational age
How do RBC count change during pregnancy?
It actually doesn’t but blood volume does so Hg, Hcrit and RCC all appear to drop
How does platelet count change?
Drops but only by dilution of increased plasma
How does WCC change?
Increases
How does coagubility change?
Increases (hypercoaguable state)
Describe some increased haematological demands of the body during pregnancy? What is the impact on management [2]
Iron demand double or triples –> Iron supplements
10-20x increase in folate needs –> Folic Acid supplements
Due to hypercoagubility pregnant women are at risk of DVTs and PEs, how can we help at risk women?
They can be given daily Dalteparin (LMWH) injections throughout pregnancy and for 6 wks after.
What happens to ESR during pregnancy? Clinical impact?
Rises, so we can’t use it as a marker of inflammation
Why do pregnant women get so much oedema? [2]
Increased blood volume and pressure coupled with drop in albumin
How do liver enzymes change during pregnancy? [2]
AST/ALT/GGT can drop
ALKP rises
Why does Alkaline phosphatase rise during pregnancy?
It’s produced by the placenta, actually it has nothing to do with the liver or gall stones etc
How does D-dimer change in pregnancy? Clinical impact?
Rises as pregnant women are hypercoagulable so unreliable as form of investigation
How do we get around the fact we can’t use a D-dimer to screen for PE?
V/Q scan instead
What are the effects of pregnancy on the adrenals? [3]
- Increased oestrogen leads to breast changes
- Protein synthesis and water retention
- Cortisol production is increased but there is NO increase in free hormone
Explain why GORD is common symptom in pregnancy [4]
- Progesterone loosens pyloric and cardiac sphincter
- Increased acid in stomach
- Reduced peristalsis
- Fetal pressure
Why and by how much does pregnancy increase Cardiac Output and Heart Rate?
NB can present as palpitations
Normal pregnancy raises CO from 30 to 50% and HR rising from 70 to 90BPM
This is to maintain a high blood flow to the foetus
How does blood pressure change physiologically during pregnancy [1] & why [4]
When does BP return to normal during pregnancy?
Drops during the 2nd trimester
A mixture of effects:
- Uteroplacental circulation expands
- SVR drops
- Blood viscosity drops
- Angiotensin sensitivity drops
Third trimester
Why does urine output increase in pregnancy? [2]
Renal plasma flow and GFR increase
Serum Urea and Creatinine also decrease
Why are pregnant women more at risk of UTIs and pyelonephritis [2]
What is the major danger of a UTI to a pregnant woman?
Urinary stasis increases - hydronephrosis is even physiological come 3rd trimester
Increased risk of preterm labour
Why are pregnant women at risk of anaemia? [2]
Because plasma volume increases by 50% but RBC mass only goes up by 25%
So a lower Haemoglobin is normal in pregnancy but you still want to ensure it doesn’t drop too low.
How does pregnancy affect blood cell counts? [2]
WBC count increases slightly
Platelet count falls (due to rise in blood volume not loss of platelets)
How does pregnancy affect the lungs?
3 actions of progesterone to ______
What is the overall change in O2 consumption and plasma PO2
Progesterone acts to reduce CO2 by:
- Increasing tidal volume
- Increased Resp rate
- Increases plasma pH
This increases O2 consumption by 20% but plasma PO2 is unchanged
How does pregnancy affect the GI system?
1 overall effect
3 clinical consequences as a result
GI motility is reduced, specifically:
Oesophageal peristalsis reduced
Gastric emptying slows
Cardiac sphincter relaxes
What hormones cause GI motility to be decreased in pregnancy? [2]
- Increased Progesterone
- Decreased Motilin
What are some symptoms of physiological changes in pregnancy? [3]
SOB from progesterone increases resp rate etc
Constipation and GORD from reduction in GI motility and pressure of foetus
Palpitations from increased HR
