Normal Pregnancy 1

Question 1

What are the changes to the uterus during pregnancy?

Answer 1

• Total volume of urine contents at term range from 5-20L (10 mL when not pregnant)
• Uterine weight about 1100g (vs. 70g)
• Unergoes hypertrophy due to estrogen and maybe progesterone
• Progressive increase in uteroplacental blood flow as gestation advances

Question 2

What are the changes to the cervix during pregnancy?

Answer 2

• Softens and undergoes cyanosis early on
• Hypertrophy and hyperplasia of glands
  
  • eversion of proliferating columnar endocervical glands
• Production of tenacious mucus rich in immunoglobulins which act as a protective barrier against normal vaginal bacteria

Question 3

What are the changes to the vagina during pregnancy?

Answer 3

• Chadwick sign - increased vaginal vascularity that accounts for bluish/purplish color during pregnancy
• Increase in mucosal thickness
• Loosening of connective tissue
• Hypertrophy of smooth muscle cells

Question 4

What are the changes to the ovaries during pregnancy?

Answer 4

• Corpus luteum present and functional until 7 weeks gestation
• Vascular pedicle increases from 0.6 cm outside of pregnancy to 2.6 cm at term
• Decidual reaction
• Luteoma -> exaggerated luteinization of ovary
• May result in maternal virilization but without effect on fetus

Question 5

What are the changes to the theca lutein cyst during pregnancy?

Answer 5

• Exaggerated physiological follicle stimulation (hyperreactio luteinalis)
• Usually bilateral cystic ovaries
• Associated with high hCG levels (multiple gestation, GTD)
• Maternal virilization occurs in 25% of patients with theca lutein cysts

Question 6

What are the cardiac changes during pregnancy?

Answer 6

• Elevation of diaphragm results in displacement of heart up and left
  
  • results in enlargement of cardiac silhouette on CXR
• ~50% increase in circulating blood volume
• ~15% increase in resting heart rate
• ~20-50% increase in CO
• **Increased heart rate **and decreased preload as a result

Question 7

What are the vascular changes during pregnancy?

Answer 7

• BP similar to pre-pregnant levels in first tirmester
  
  • ​Initial decrease in SVR
• BP nadirs in second trimester
  
  • systolic decreases 5-10 mmHg
  • diastolic decreases 10-15 mmHg
• BP increases back to baseline values in third trimester
  
  • Impairment of venous return by mechanical uterin obstruction overall increases SVR

Question 8

What are the respiratory changes during pregnancy?

Answer 8

• Diaphragm elevates, subcostal angle increases, and thoracic circumference increases
• No change in respiratory rate
• 40% increase in tidal volume
• 20% decrease in residual volume and functional residual capacity
• Dyspnea of pregnancy
  
  • Results from increased TV that lowers maternal PCO2, which is required for proper diffusion of CO2 from fetus to mother
  • Decreased PCO2 is compensated by increase excretion of bicarbonate

Question 9

What are the gastrointestinal changes during pregnancy?

Answer 9

• Displacement of stomach and intestines by enlarging uterus
• Gastric emptying time unchanged during pregnancy, but increases substantially during labor (especially after administration of analgesics)
• Liver itself has minimal changes except increased blood flow
• Certain hepatic lab tests “abnormal” but related to pregnancy changes and not pathology
  
  • Alk phos
  • Albumin

Question 10

What are the renal/urinary changes during pregnancy?

Answer 10

• Slight increase in kidney size
• GFR increases by up to 50% by mid-pregnancy, with even greater increases in RPF
• Serum Cr decreases normally in pregnancy
• Uterine displacement of ureters results in ureteral dilatation
• Increased bladder pressure but with compensation by elongation of urethra, which increases intraurethral pressure and maintains continence

Question 11

What is the purpose of hypervolemia in pregnancy?

Answer 11

• Meets metabolic demands of the enlarged uterus and its hypertrophied vascular system
• Provides nutrients to support rapidly growing placenta/fetus
• Protects mother (and thus fetus) against deleterious effects of impaired venous return in supine and erect positions
• Protects mother against adverse effects of blood loss associated with parturition

Question 12

What are the changes to erythrocytes/hemoglobin in pregnancy?

Answer 12

• Erythroid hyperplasia occurs and slight increase in reticulocyte count (not abnormally high)
• Erythrocyte volume increases by about 450 mL by the end of pregnancy
• Increase in erythrocytes not as great as increase in blood volume à slight decrease in Hb and Hct in pregnancy (Hb < 11.0 g/dL considered anemic)

Question 13

What are the iron requirements of pregnancy?

Answer 13

1000 mg Fe required for pregnancy, with about 1/3 transferred to fetus and placenta

Question 14

How do leukocytes change in pregnancy?

Answer 14

• Varies considerably in pregnancy, but not abnormal for slight leukocytosis to be present
• Distribution of cell types altered in pregnancy
  
  • ↑ granulocytes and CD8 lymphocytes
  • ↓ CD4 lymphocytes and monocytes

Question 15

What are the changes to coagulation/firbrinolysis during pregnancy?

Answer 15

• Both augmented but remain balanced to maintain homeostasis
• All clotting factors increase with exception of factor XI and factor XIII
• Protein S decreases in pregnancy, as does activated protein C
• tPA increases throughout pregnancy
• Minimal decrease in platelet count in pregnancy (attributed to hypervolemia)

Question 16

What are the endocrine changes in pregnancy?

Answer 16

• Number of circulating hormones increased in pregnancy
  
  • Estrogen
  • Progesterone
  • Prolactin
  • PTH
  • Aldosterone
  • Cortisol
  • DHEA
  • Androstenedione
  • Testosterone
• Thyroid
  
  • TBG increases with pregnancy
  • Total T4 and total T3 increase in pregnancy, but TSH and TRH remain stable