Physiology of Pregnancy

Question 1

Hematologic changes in pregnancy

• What happens to volume?
• What happens to blood proteins?

Answer 1

• Volume expands by up to 40% at term, resulting in physiologic anemia b/c plasma volume expands more than erythrocyte volume
• Decreased albumin –> decreased colloid oncotic pressure –> fluid shifts to interstitial spaces –> edema

Question 2

Immune changes during pregnancy

• What is the general state of the mother’s immune system during pregnancy?
• What antibodies cross placenta to reach fetus during development?
• What antibodies are present in breast milk?

Answer 2

• Supression of humoral and immune cell mediated immunological function to accomodate “foreign” fetus, white cell count increases but their function is depressed
• IgG
• IgA

Question 3

What is Virchow’s Triad? How does it relate to pregnancy?

Answer 3

All 3 elements of Virchow’s triad are present during pregnancy

1. Hypercoagulable blood
   
   • Increase in procoagulation factors
   • Decrease in anticoagulation factors
2. Stasis of blood
   
   • Venous compression due to head of fetus
   • Progesterone dilation of all smooth muscle dilates venous system
3. Vascular damage
   
   • Due to delivery (natural is less bad here than cesarian)

Question 4

The risk of DVT is […] postpartum and […] delivery further increases risk of DVT

Answer 4

High

Cesarean

Question 5

Cardiovascular changes during pregnancy

• Cardiac output?
• Sounds on ascultation?
• Location of heart?

Answer 5

Question 6

Cardiovascular Changes During Pregnancy (contd)

• Resistance?
• Blood pressure?

Answer 6

• Systemic vascular resistance decreases due to progesterone causing relaxation on vascular smooth muscle
• Decrease in BP due to decrease in TPR, additionally, can experience hypotension when laying down completely due to compression of IVC by fetus

Question 7

When a person is not pregnant, […]% of blood flow goes to uterus. When a person is pregnant […]% of bloow flow goes to uterus.

Answer 7

2

20

Question 8

Respiratory changes during pregnancy

• Diaphragm?
• Ventilation?
• Volumes?
• RR?
• PCO2?
• HCO3-?

Answer 8

• Rises 4cm at term
• Increases –> resp alkalosis
• Tidal volume increases –> barrel chested
• No change in RR
• Decreases
• Decreases

Question 9

GI changes during pregnancy

• Pressure?
• @ inreased risk for what GI issues?

Answer 9

• Increased intra-abdominal pressure
• Progesterone relaxation of smooth muscle increases risk for:
  
  • GERD (relaxed UES)
  • Constipation (relaxed SM of GI tract = decreased motility)
  • Hemmorrhoids (relaxation of VSM)
  • Gall stones

Question 10

GI Changes during pregnancy contd

• Why do we see nausea and vomiting in pregnancy
• What can you not assume if a pregnant woman has nausea and vomiting?

Answer 10

• Placental hormones contribute to these symptoms, severity correlates with rises in hCG
• Can’t assume that it’s b/c they’re pregnant, there are many non-obstetric reasons why they may have those symptoms (i.e. appendicitis –> see graphic, location of appendix changes during pregnancy)

Question 11

Endocrine Changes During Pregnancy

• Do thyroid hormones change / why?
• What do these changes correspond with temporally?
• Why are some pregnant women misdiagnosed with subclinical hyperthyroidism?
• Effect of thyroid hormones on fetus?
• True/False: when measuring thyroid hormones in pregnant women, you compare their values to normal reference values.

Answer 11

• Increased production of T4 in mother to meet increased metabolic demands of fetus. Additionally, TBG increases and after slight rise in T4 in first trimester, free T4 levels remain stable.
• Free T4 rises and peaks in same pattern as hCG
• hCG and TSH are both glycoproteins and share an alpha subunit so hCG can stimulate the thyroid in the first trimester when it’s levels are increasing and if so this would lead to a decrease in TSH leading Dr to believe the person had hyperhtyroidism but really they don’t
• Maternal T4 crosses placenta until fetus makes its own thyroid hormones
• False, Reference ranges are defined by trimeter

Question 12

Metabolic changes during pregnancy

• What is hPL?
• What does it do?

Answer 12

• hPL is in the same family of hormones as growth hormone, it is a somatotropin secreted by the placenta during fetal development, rises throughout pregnancy
• Functions:
  
  • stimulate insulin-like growth factor (IGF) production and modulate intermediary metabolism, resulting in an increase in the availability of glucose and amino acids to the fetus
  • Increases insulin resistance in mother to increase amount of glucose that is available for fetus –> responsible for development of gestation diabetes in some women
  • Promotes lipolysis

Question 13

Renal changes during pregnancy

• GFR?
• What compound is seen in urine that normally isn’t?
• Effect on creatinine?
• Size of kidneys?

Answer 13

• GFR increases up to 50% due to increased volume in mother
• Glucose in urine is normal in pregnancy
• Creatinine should decrease, value > 0.9 in a normal person would not be considered abnormal but this would be concerning in pregnant person
• Mild hydronephrosis possible

Question 14

Skin changes during pregnancy

• What are some common changes that can be seen in skin during pregnancy?
• What changes can be seen in hair?

Answer 14

• Hyperpigmentation
  
  • Melasma
  • Linea Nigra
  • Stria gravidarum (stretch marks)
• During pregnancy, growth phase of hair cycle (anogen) increases, post pregnancy telogen phase (shedding) increases –> makes women think their hair is all falling out but this is normal return to baseline

Question 15

Skin changes during pregnancy contd

• What changes could be seen in the skin of the limbs, vagina, and hands?

Answer 15

Question 16

Discuss normal weight gain for pregnant women based on their pre-pregnancy weight.

Answer 16