OnlineMedEd: Obstetrics - "Physiology of Pregnancy"

Question 1

How do SVR, SV, EF, HR, and CO change in a pregnant woman?

Answer 1

• SVR decreases because of increased vasculature (i.e., the placenta)
• SV stays the same
• EF also stays the same
• HR increases by about 15% during pregnancy (and substantially more in labor)
• CO increases

Question 2

The delivery of oxygen is equal to _____________.

Answer 2

CO x Hgb x Sp

Question 3

Why does hemoglobin decrease in pregnancy?

Answer 3

Hgb = RBC/plasma

The RBCs do increase, but the plasma increases even more.

Question 4

Minute ventilation is equal to __________.

Answer 4

tidal volume x respiratory rate

Question 5

Why do examiners love to trick you on questions about the pulmonary system in pregnancy?

Answer 5

You’d think that women would take shallower breaths during pregnancy, but actually they take deeper breaths – it’s the respiratory rate that decreases. Minute ventilation stays the same.

Question 6

The “three A’s” of platelet hemostasis are _____________.

Answer 6

adhesion, activation, and aggravation

Question 7

Which of the three platelet steps is affected in pregnancy?

Answer 7

Adhesion

The amount of von Willebrand factor is increased.

Question 8

Which factors in the clotting cascade are affected in prenancy?

Answer 8

• V, VII, VIII, IX, X, and II are increased
• C and S are decreased

Both of these lead to a hypercoagulable state.

Question 9

Fibrinogen is ___________ in pregnancy.

Answer 9

elevated

Thus, a normal fibrinogen in pregnancy is indicative of clotting.

Question 10

A normal creatinine in pregnancy is ______________.

Answer 10

0.4 - 0.8

Question 11

How much weight should a woman gain per week in pregnancy?

Answer 11

It depends on her starting BMI: 
• Under 18.5: 1 lb / week
• 18.5 - 25: 0.75 lbs/week
•25 - 30: 0.50 lbs/week
• Over 35: 0.25 lbs/week

Notice that it goes down by 0.25 per BMI category.