Physiology in Pregnancy

Question 1

List some General changes to the body during pregnancy?

Answer 1

• Increased lumbar curvature to compensate for the belly weight
• Fatigue
• Reflux due to loosening of GI sphincters
• Oedema
• Breast
• Thyroid (iodine used up so thyroid enlarges to compensate)
• General Immunosuppression
• Weight Gain

Question 2

How does the breast change durine pregnancy?

Answer 2

• 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

Question 3

How does blood volume change during pregnancy?

Answer 3

Up to 50-70% more blood volume while pregnant

Question 4

How does heart activity change during pregnancy?

Answer 4

SV & HR rise leading to a much higher CO. Most women have Sinus Tachycardia during pregnancy

SVR also drops significantly

Question 5

Why does CO increase so much during pregnancy?

Answer 5

Because O2 consumption goes way up

Question 6

How can changing position affect a pregnant woman’s CO?

Answer 6

If they lie supine the foetus presses on the IVC reducing venous return and so reducing CO.

Question 7

Why is it important to understand how a pregnant woman’s CO decreases in supine position?

Answer 7

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

Question 8

How does increased CO affect risk of heart problems?

Answer 8

Increased CO means the heart muscle requires more O2. Thus there’s an increased risk of angina or MI

Question 9

How does blood volume & blood pressure change during labour?

Answer 9

Every contraction pushes blood from uterus into systemic circulation (Autotransfusion) - think up to 500ml per contraction

This increases blood volume and BP so is dangerous, especially in people with existing BP problems or stenotic lesions

Question 10

How does CO change durine labour?

Answer 10

Increases by 10% during labour and up to 80% in the first hr post-delivery. So they’re still at massive risk after delivery.

Question 11

When does the CV system return to normal after pregnancy?

Answer 11

Most are back to normal within 3 months

Question 12

How long does BP take to return to normal?

Answer 12

It falls and icnreases again in the first 7 days but returns to pre-preg levels by 6wks

Question 13

How long before HR returns to normal?

Answer 13

2 wks

Question 14

How long before CO returns to normal?

Answer 14

incerases by 80% in first hour post delivery then falls back to normal over 2-4 weeks (i think)

Question 15

How do the lungs change during pregnancy?

Answer 15

40-50% increae in ventilation with RR & TIdal volume increasing. (to compensate for increases O2 demand)

But PEFR & FEV1 are unchanged

Question 16

How do O2/CO2 levels change during pregnancy?

Answer 16

O2 rises and CO2 drops due to increased ventilation. So looks like compensated respiratory alkalosis on blood gases.

Question 17

How does the renal system change structurally during pregnancy?

Answer 17

It dramatically dilates (particularly on the right). Both the ureters and kidneys dilate due to pressure from uterus and progesterone

Question 18

How does function of the kidneys change in pregnancy?

How does this affect blood levels of kidney marker things

Answer 18

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

Question 19

What is uric acid level used for in pregnancy?

Answer 19

A marker of pre-eclampsia

It also increases with gestation so the level can be predicted based on gestational age

Question 20

How do RBC count change during pregnancy?

Answer 20

It actually doesn’t.

but blood volume does so Hg, Hcrit and RCC all appear to drop

Question 21

How does platelet count change?

Answer 21

Drops but only by dilution of increased plasma

Question 22

How does WCC change?

Answer 22

Increases

Question 23

How does coagubility change?

Answer 23

Increases (Hypercoaguable)

Question 24

Describe some increased haematological demands of the body during pregnancy?

Answer 24

Iron demand double or triples –> Iron supplements

10-20x increase in folate needs –> Folic Acid supplements

Question 25

Due to hypercoagubility pregnant women are at risk of DVTs & PEs, how can we help at risk women?

Answer 25

They can be given daily Dalteparin (LMWH) injections throughout pregnancy and for 6 wks after.

Question 26

What happens to ESR during pregnancy?

Answer 26

Rises, so we can’t use it as a marker of inflammation

Question 27

Why do pregnant women get so much oedema?

Answer 27

Increased blood volume & pressure coupled with drop in albumin

Question 28

How do liver enzymes change during pregnancy?

Answer 28

AST/ALT/GGT can drop

ALKP rises

Question 29

Why does Alkaline phosphatase rise during pregnancy?

Answer 29

ITs produced by the placenta, actually got nothing to do with the liver or gall stones etc

Question 30

How does D-dimer change?

Answer 30

Rises, cos they’re hypercoagulable

Ergo we can’t use as we can’t know what normal is

Question 31

How do we get around the fact we can’t use a D-dimer to screen for PE?

Answer 31

Just have to send everyone we think might have it for a V/Q scan