Maternal-Fetal Physiology

Question 1

Albumin in pregnancy

Answer 1

There is a physiologic decrease in albumin during pregnancy, effectively a dilutional effect

Question 2

Increase in pituitary size during pregnancy

Answer 2

This is normal and due to the hyperplasia of lactotrophes. Meanwhile, gonadotropes are hypoplastic.

Question 3

Parathyroids in pregnancy

Answer 3

Undergo hyperplasia in order to meet the calcium needs of fetal bone formation

Question 4

Physiologic increase in cortisol during pregnancy

Answer 4

Secondary to an estrogen-mediated increase in cortisol binding globulin

May contribute to insulin resistance in pregnancy (along with HPL) and development of striae.

Question 5

As part of the physiologic change in blood pressure regulation during pregnancy, there is a decrease in sensitivity to ___.

Answer 5

As part of the physiologic change in blood pressure regulation during pregnancy, there is a decrease in sensitivity to angeiotensin II and norepinephrine.

Question 6

Risk of pulmonary edema in pregnancy

Answer 6

1. Decreased SVR
2. Increased PVR
3. Decreased colloidal osmotic pressure (hypoalbuminemia of pregnancy)
4. Associated risk of dilated cardiomyopathy in pregnancy

Question 7

Hematologic changes in pregnancy

Answer 7

• Increased plasma volume
• Increase in absolute circulating RBCs, but still physiologic anemia
  
  • Consequential 2-3 fold increase in EPO
• Physiologic thrombocytopenia
• Physiologic granulocytosis (elevated estrogen and cortisol levels)
• Increase in pro-coagulant factors, decrease in anti-coagulant factors (5x risk of clots)

Question 8

Pulmonary changes in pregnancy

Answer 8

• Decreased TLC and FRC from mass effect of uterus
• Hyperventilation to achieve adequate oxygen supply for fetus
  
  • Chronic compensated respiratory alkalosis

Question 9

Renal and urologic changes in pregnancy

Answer 9

• Increased baseline RAAS signaling to maintain volume
• Increased GFR and clearance
• Dilation of ureters (progesterone-mediated smooth muscle relaxation)
• Compression of bladder and reduced bladder capacity

Question 10

Hemorrhoids in pregnancy

Answer 10

Increased portovenous pressure in pregnancy causes dilation of the rectal veins -> hemorrhoids

Question 11

Although pregnant women have a significant increased risk of GERD, they have a decreased risk of peptic ulcer disease. How can these facts be reconciled?

Answer 11

• The GERD is due to relaxation of the LES by progesterone and relaxin and due to mass effect on the stomach by the uterus
• However, risk of PUD decreases because of circulating placental histamines, which increases protective mucous secretion in the stomach

Question 12

Immune effects of progesterone and relaxin

Answer 12

• These together inhibit maternal T cell function, preventing allograft rejection

Question 13

IVC syndrome

Answer 13

• Caused by compression of the IVC by the gravid uterus
• Dizziness, lightheadedness, syncope

Question 14

Maternal blood pressure past the first trimester is often highest when ___

Answer 14

Maternal blood pressure past the first trimester is often highest when seated

Not lying supine! This is because of the gravid uterus

Question 15

Dyspnea during pregnancy

Answer 15

• May be, and is most likely, physiologic
  
  • Physiologic response to a low arterial pCO₂ from hyperventilation
• However, it still requires workup, since it is potentially dangerous to the fetus (moreso than mom) if we miss something

Question 16

Changes in urinalysis with pregnancy

Answer 16

Due to the increase in GFR by ~50%, there is an increased load of various solutes presented to the nephron. Consequentially, there will be an elevation in the urinary excretion of most components. This explains why there is physiologic trace glucosuria during pregnancy.

However, trace proteinuria is NOT normal during pregnancy. Trace protein still should not be making it through. If observed, his may be a sign of pre-eclampsia or other illness.

Question 17

Normal rise in beta hCG

Answer 17

50% every 48 hours

However, even 35% in 48 hours can be normal

Question 18

___ is the major cause of nausea and vomiting in pregnancy, which is why hyperemesis gravidarum is seen with multiple gestations and molar pregnancies.

Answer 18

hCG is the major cause of nausea and vomiting in pregnancy, which is why hyperemesis gravidarum is seen with multiple gestations and molar pregnancies.