Physiology in Pregnancy Flashcards
List some General changes to the body during pregnancy?
- Increased lumbar curvature to compensate for the belly
- Fatigue
- Reflux due to loosening of GI sphincters
- Oedema
- Breast
- Thyroid (iodine used up so thyroid enlarges to compensate)
- General Immunosuppression
- Weight Gain
How does the breast change durine pregnancy?
- 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 trimester
How does blood volume change during pregnancy?
Up to 50-70% more blood volume while pregnant
How does heart activity change during pregnancy?
SV & 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?
If they lie supine the foetus presses on the IVC reducing venous return and so reducing CO.
Why is it important to understand how a pregnant woman’s CO decreases in supine position?
Trying to do CPR & 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?
Increased CO means the heart muscle requires more O2. Thus there’s an increased risk of angina or MI
How does blood volume & pressure during labour?
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. So they’re still at massive risk after delivery.
When does the CV system return to normal after pregnancy?
Most are back to normal within 3 months
How long does BP take to return to normal?
It falls and icnreases again in the first 7 days but returns to pre-preg levels by 6wks
How long before HR returns to normal?
2 wks
How long before CO returns to normal?
incerases by 80% in first hour post delivery then falls back to normal over 24 weeks
How do the lungs change during pregnancy?
40-50% increae in ventilation with RR & TIdal volume increasing. (to compensate for increases O2 demand)
But PEFR & FEV1 are unchanged
How do O2/CO2 levels change during pregnancy?
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?
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?
Renal plasma flow goes up by 60-80% by end of trimester 2
–> Increased GFR & Creatinine clearance
–> Urea & Creatinine fall
Protein excretion goes up ergo 24hr urine protein rises and total protein/Albumin drop
Urate rises with gestation
Glycosuria is common
What is uric acid level used for in pregnancy?
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)
Describe some increased haematological demands of the body during pregnancy?
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 & 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?
Rises, so we can’t use it as a marker of inflammation
Why do pregnant women get so much oedema?
Increased blood volume & pressure coupled with drop in albumin
How do liver enzymes change during pregnancy?
AST/ALT/GGT can drop
ALKP rises
Why does Alkaline phosphatase rise during pregnancy?
ITs produced by the placenta, actually got nothing to do with the liver or gall stones etc
How does D-dimer change?
Rises, cos they’re hypercoagulable
Ergo we can’t use as we can’t know what normal is
How do we get around the fact we can’t use a D-dimer to screen for PE?
Just have to send everyone we think might have it for a V/Q scan
