1. PATRICK DUFF, M.D. UNIVERSITY OF FLORIDA
MATERNAL PHYSIOLOGY
PATRICK DUFF, M.D.
UNIVERSITY OF FLORIDA

2. MATERNAL PHYSIOLOGY OVERVIEW
Placenta
Hormone production
Mechanisms of placental transfer
Changes in uterus
Cardiopulmonary changes
Hematologic changes
Alterations in GI function
Renal function changes

3. PLACENTAL HORMONE PRODUCTION

4. HORMONE PRODUCTION BY THE PLACENTA
FUNCTION
Human placental lactogen (HPL)
Antagonizes insulin  spares glucose for use by fetus
Enhances lipolysis provides alternate fuel source for mother
Human chorionic gonadotropin (hCG)
Stimulates corpus luteum to secrete estradiol and progesterone

5. MECHANISMS OF PLACENTAL TRANSFER
EXAMPLES
Simple diffusion
Water, oxygen, carbon dioxide
Facilitated diffusion
Glucose
Active transport
Amino acids, iron
Pinocytosis
Drugs, immunoglobulins

6. CHANGES IN UTERUS Uterine blood flow increases significantly
Uterine blood flow may approach 500 – 750 cc/ minute
Hemorrhage is key cause of maternal death
Status
% of C.O. Perfusing Uterus
Non-pregnant
< 1 %
Pregnant
15-20%

7. DISTRIBUTION OF UTERINE BLOOD FLOW DURING PREGNANCY

8. CARDIOVASCULAR CHANGES DURING PREGNANCY
CARDIAC FUNCTION
PERCENT INCREASE IN PREGNANCY
Heart rate
5-15%
Stroke volume
25-30%
Cardiac output
35-50%

9. CHANGES IN CARDIAC OUTPUT DURING LABOR
STAGE OF LABOR
ADDITIONAL PERCENT INCREASE IN CARDIAC OUTPUT
Early first
15-20%
Late first
30-35%
Second
35-40%

10. DANGEROUS CARDIAC DISEASES IN PREGNANCY
Stenotic valve lesions
Ischemic heart disease
Marfan syndrome
Eisenmenger’s syndrome
Primary pulmonary hypertension

11. PULMONARY FUNCTION ALTERATIONS IN PREGNANCY

12. PULMONARY FUNCTON ALTERATIONS IN PREGNANCY
PULMONARY VOLUME
CHANGE
Inspiratory reserve volume
No change
Tidal volume
Increased
Expiratory reserve volume
Decreased
Residual volume

13. PULMONARY FUNCTION ALTERATIONS IN PREGNANCY
PULMONARY CAPACITY
CHANGE
Inspiratory capacity (IRV + TV)
Increased
Vital capacity (IRV + TV + ERV)
Unchanged
Functional residual capacity (ERV + RV)
Decreased
Total lung capacity (IRV+TV+ERV+RV)

14. ALTERATIONS IN ARTERIAL BLOOD GASES
Increased pH
Decreased pCO2
Decreased HCO3
PARTIALLY COMPENSATED RESPIRATORY ALKALOSIS

15. HEMATOLOGIC ALTERATIONS IN PREGNANCY
COMPONENT
PERCENT CHANGE
Blood volume
30-50%
Plasma volume
50%
Red cell number
30%

16. PRINCIPAL CAUSES OF ANEMIA IN PREGNANCY
ETIOLOGY
KEY DIAGNOSTIC TEST(S)
Iron deficiency
RBC indices, serum ferritin
Hemodilution
RBC indices
Folate deficiency
RBC indices, serum folate
B 12 deficiency
Hemoglobinopathy
Hgb electrophoresis

17. PERIPHERAL BLOOD SMEARS

18. HEMATOLOGIC ALTERATIONS IN PREGNANCY
CELL LINE
CHANGE
White blood cells
Slight increase
Platelets*
Unchanged to slight decease
* Most common causes of thrombocytopenia –
pre-eclampsia and gestational thrombocytopenia

19. COAGULATION CHANGES IN PREGNANCY
Enhanced hepatic synthesis of I, II, VII, VIII, IX, and X
Placenta  III (tissue thromboplastin)
Platelets  aggregate more readily

20. VIRCHOW’S TRIAD THROMBOSIS
Venous stasis
Alteration in venous wall
Hyper-coagulable state

21. GASTROINTESTINAL ALTERATIONS IN PREGNANCY
CLINICAL CONSEQUENCE
Delayed gastric emptying (gastroparesis)
GERD
Early satiety
Biliary duct stasis
Cholelithiasis
pancreatitis
Change in location of appendix
Delay in diagnosis

22. CHANGE IN ANATOMIC LOCATION OF APPENDIX IN PREGNANCY

23. GASTROINTESTINAL ALTERATIONS IN PREGNANCY
CONSEQUENCE
Increased intra-abdominal pressure
Hiatal hernia
Delayed colonic empyting
Constipation

24. RENAL FUNCTION ALTERATIONS IN PREGNANCY
Renal blood flow increases 30 – 40 % above pre-pregnancy levels
GFR ( creatinine clearance) increases
Serum BUN, creatinine, and uric acid decrease

25. FREQUENCY OF UTIs IN PREGNANCY
TYPE OF INFECTION
FREQUENCY
Asymptomatic bacteriuria
5-10%
Acute cystitis
2-3%
Pyelonephritis
1-2%

26. MICROBIOLOGY OF UTIs IN PREGNANCY

27. INCREASED RISK OF PYELONEPHRITIS IN PREGNANCY
Progesterone inhibits ureteral peristalsis
Mechanical compression of ureter by gravid uterus
Complications of pyelonephritis
Preterm labor
Sepsis and ARDS

28. INCREASED RISK OF NEPHROLITHIASIS
Increased concentration of calcium in the urine
Urinary stasis
Most common stones
Calcium oxalate
Struvite

29. MATERNAL PHYSIOLOGY SUMMARY
ORGAN SYSTEM
KEY TEACHING POINTS
Cardiac
Danger of stenotic lesions and pulmonary hypertension
Pulmonary
VC – unchanged
FRC – decreased
ABGs – compensated respiratory alkalosis

30. MATERNAL PHYSIOLOGY SUMMARY
ORGAN SYSTEM
KEY TEACHING POINTS
Hematologic
Increased frequency of anemia, DVT, PE GI
Increased frequency of GERD, gall bladder disease, and constipation
Renal
Increased RBF and GFR
Increased risk of ascending UTI
Increased risk of nephrolithiasis