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Maternal Physiology Lecture

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A lecture for medical students detailing the physiologic changes that take place during pregnancy

Maternal Physiology Lecture

  1. 1. MATERNAL PHYSIOLOGY <ul><ul><li>Chukwuma I. Onyeije, M.D. </li></ul></ul><ul><ul><li>Atlanta Perinatal Associates </li></ul></ul><ul><ul><li>Clinical Assoc. Professor </li></ul></ul><ul><ul><li>Morehouse School of Medicine </li></ul></ul><ul><ul><li>http://maternalfetalmedicineblog.com </li></ul></ul><ul><ul><li>http://onyeije.net/present </li></ul></ul>
  2. 2. Objectives <ul><li>Detail normal physiologic changes in the following maternal systems: </li></ul><ul><ul><li>Cardiovascular </li></ul></ul><ul><ul><li>Respiratory </li></ul></ul><ul><ul><li>Renal </li></ul></ul><ul><ul><li>Hematologic </li></ul></ul><ul><ul><li>Gastrointestinal </li></ul></ul><ul><ul><li>Reproductive systems. </li></ul></ul><ul><li>Describe the implications for these changes for normal and abnormal pregnancies. </li></ul>
  3. 3. Objectives <ul><li>Review nutritional requirements normal pregnancy </li></ul><ul><li>Review components and reasons for the medical evaluation at the first prenatal visit </li></ul><ul><li>Give the reason for routine laboratory tests obtained early in pregnancy. </li></ul>
  4. 4. BULLET POINTS: <ul><ul><li>Dilutional anemia of pregnancy: </li></ul></ul><ul><ul><li>Lower hematocrit due to expansion of plasma volume which is greater than the increase in red blood cell mass </li></ul></ul>
  5. 5. BULLET POINTS: <ul><ul><li>Pregnancy is a Hypercoagulable state: </li></ul></ul><ul><ul><li>Increased risk for venous clotting episodes </li></ul></ul>
  6. 6. BULLET POINTS: <ul><ul><li>Hegar's sign: </li></ul></ul><ul><ul><li>Cervix appears bluish and engorged </li></ul></ul>
  7. 7. BULLET POINTS: <ul><ul><li>MSAFP </li></ul></ul><ul><ul><li>(Maternal serum </li></ul></ul><ul><ul><li>alpha-fetoprotein)‏ </li></ul></ul><ul><ul><li>Screening test of maternal blood done in the early second trimester to screen pregnant women for fetal anomalies and chromosomal abnormalities </li></ul></ul>
  8. 8. BULLET POINTS: <ul><ul><li>Bacterial vaginosis: </li></ul></ul><ul><ul><li>Bacterial infection of the vagina associated with preterm labor and birth </li></ul></ul>
  9. 9. BULLET POINTS: <ul><ul><li>Rhogam: </li></ul></ul><ul><ul><li>An antibody preparation of anti-Rh factor given to Rh negative women to prevent Rh isoimmunization </li></ul></ul>
  10. 10. BULLET POINTS: <ul><ul><li>Neural tube defect (NTD): </li></ul></ul><ul><ul><li>An abnormality in closure of the neural tube, resulting in a spectrum of anomalies from anencephaly (no cranium or cerebrum) to spina bifida </li></ul></ul>
  11. 11. BULLET POINTS: <ul><ul><li>Intrauterine growth restriction (IUGR): pathological condition of abnormal placentation resulting in an undergrown fetus </li></ul></ul><ul><ul><li>Small-for-gestational age (SGA): the lower 10% of birthweights </li></ul></ul>
  12. 12. BULLET POINTS: <ul><ul><li>Large-for-gestational age (LGA): the upper 10% of birthweights </li></ul></ul><ul><ul><li>Macrosomia: an abnormally large infant (usually > 4000 gm) </li></ul></ul>
  13. 13. The primary goal of prenatal care is to deliver a healthy term infant without impairing the mothers health and to identify and optimally treat the high-risk mother.
  14. 14. The vast majority of pregnancies are uncomplicated. Excessive intervention during pregnancy can result in less than optimal outcome
  15. 15. THE CARDIOVASCULAR SYSTEM:
  16. 16. THE CARDIOVASCULAR SYSTEM: <ul><li>Cardiac output increases 30-50% </li></ul><ul><li>Stroke volume increases about 10- 15% </li></ul><ul><li>Pulse increases about 15-20 bpm </li></ul><ul><li>Systolic ejection murmur and S3 gallop are seen in 90% of pregnant women </li></ul>
  17. 17. CARDIAC OUTPUT DURING PREGNANCY
  18. 18. Peripheral vascular resistance falls Blood pressure falls during the second trimester and then returns to normal during the third trimester
  19. 19. CLINICAL SIGNIFICANCE: Many of the NORMAL effects of pregnancy mimic heart failure (edema, gallops, dyspnea, distended neck veins, abnormal cardiac silhouette on CXR, EKG changes).
  20. 20. THE RESPIRATORY SYSTEM:
  21. 21. Lung volumes changes in pregnancy
  22. 22. NO CHANGE: Respiratory rate, Vital capacity, Inspiratory reserve volume
  23. 23. DECREASED: Functional residual capacity Expiratory reserve volume Residual volume Total lung capacity
  24. 24. INCREASED: Inspiratory capacity Tidal volume
  25. 25. BLOOD GASES: CLINICAL SIGNIFICANCE: The normal pregnant woman has a compensated respiratory alkalosis and a diminished pulmonary reserve.
  26. 26. THE RENAL SYSTEM:
  27. 27. ANATOMIC RENAL CHANGES: Kidneys increase in size and weight, Dilatation of ureters (R > L) Bladder becomes an intra-abdominal organ
  28. 28. HEMODYNAMIC RENAL CHANGES: GFR increases 50%, Renal plasma flow increases by 75% Creatinine clearance increases to 150-200 cc/min
  29. 29. METABOLIC RENAL CHANGES <ul><ul><li>BUN and serum creatinine decrease by 25% Increase in tubular reabsorption of sodium </li></ul></ul><ul><ul><li>Increase in glucose excretion </li></ul></ul>
  30. 30. METABOLIC RENAL CHANGES <ul><ul><li>Plasma osmolarity decreases about 10 mOsm/kg H2O </li></ul></ul><ul><ul><li>Marked increase in renin and angiotensin levels, BUT markedly reduced vascular sensitivity to their hypertensive effects </li></ul></ul>
  31. 31. CLINICAL SIGNIFICANCE of RENAL CHANGES <ul><ul><li>: </li></ul></ul><ul><ul><li>Pregnant women are at increased risk for prone to pyelonephritis </li></ul></ul><ul><ul><li>Pregnant women are at increased risk for bladder rupture during abdominal trauma. </li></ul></ul>
  32. 32. THE HEMATOLOGIC SYSTEM
  33. 33. Plasma volume and RBC mass Plasma volume increases by about 50% RBC volume increases by about 30%
  34. 34. Plasma volume and RBC mass END RESULT: ”Dilutional anemia of pregnancy&quot;, Average hemoglobin during pregnancy is 11.5 g/dl
  35. 35. Plasma volume and RBC mass
  36. 36. OTHER HEMATOLOGIC CHANGES: WBC count increases Platelet count decreases, but stays within normal limits
  37. 37. COAGULATION SYSTEM: Pregnancy is a &quot;hypercoagulable state&quot; Increased levels of fibrinogen, factor VII-X The placenta produces a plasminogen activator inhibitor
  38. 38. CLINICAL SIGNIFICANCE: Blood loss is well-tolerated during labor. However: maternal vital signs DO NOT change for blood loss of up to 1500 cc, Therefore: vital signs cannot be trusted as an indicator of blood loss.
  39. 39. THE GASTROINTESTINAL AND REPRODUCTIVE SYSTEMS
  40. 40. Gastrointestinal System Decreased motility, due to influence of progesterone Reduced gastric acid secretion
  41. 41. Gastrointestinal System CLINICAL SIGNIFICANCE: A pregnant woman is considered to have a full stomach even if she has had nothing to eat or drink for several hours. Peptic ulceration is rare during pregnancy.
  42. 42. Reproductive System Weight of the Uterus increases from 70 gm to 1100 gm Blood flow: increases to about 750 cc/min, or 10-15% of cardiac output
  43. 43. NUTRITIONAL CONSIDERATIONS DURING PREGNANCY
  44. 44. PREGNANCY WEIGHT GAIN BY ORGAN SYSTEM: Fetus: 7 pounds Placenta and amniotic fluid -- 3 pounds Blood volume-- 4 pounds Breasts-- 2 pounds Maternal fat-- 4 pounds ANTICIPATED TOTAL: 20 pounds
  45. 45. Average weight gain THERE IS NO SUCH THING AS “OPTIMAL” WEIGHT GAIN Normal BMI: 20 lbs Underweight BMI: 30 lbs Overweight BMI 16 lbs
  46. 46. Daily dietary requirements Calories: Increased 15% to ~ 2200 cal/day Protein: An additional 10 to 30 gm /day ~ 75 gm/day total Iron supplementation 30 to 60 mg per day
  47. 47. Calcium: 1200 mg needed per day, usually provided by a quart of milk per day or 2 Tums/day, Folate: supplement 200 to 400 mcg per day In women with a prior history of having a baby with a neural tube defect, supplementing with 4 mg per day (4000 mcg) has been shown to decrease the risk of a recurrence in the next pregnancy
  48. 48. The pregnant patient is best served by having a healthy balanced diet with iron and folate supplementation. Only rarely are other vitamin supplements necessary
  49. 49. PRENATAL CARE
  50. 50. The first prenatal visit Decide: Is this patient normal or high-risk?
  51. 52. COMMON COMPLAINTS OF PREGNANCY
  52. 53. Nausea and vomiting: usually dissipates by 15 weeks
  53. 54. Constipation: common throughout pregnancy
  54. 55. Heartburn: often worsens as pregnancy progresses
  55. 56. Vaginitis: treat only if symptomatic
  56. 57. Varicose veins: treat symptomatically
  57. 58. Headaches
  58. 59. Lower extremity edema is very common
  59. 60. Backache: Lordosis is common with change in the center of gravity
  60. 61. Faintness and light-headedness
  61. 62. Carpal tunnel syndrome
  62. 63. REVIEW QUESTIONS:
  63. 64. <ul><ul><li>Which of the following INCREASES in pregnancy? </li></ul></ul><ul><ul><ul><li>FRC </li></ul></ul></ul><ul><ul><ul><li>ERV </li></ul></ul></ul><ul><ul><ul><li>RV </li></ul></ul></ul><ul><ul><ul><li>TV </li></ul></ul></ul>
  64. 65. <ul><ul><li>During which of the following states is the blood pressure lowest? </li></ul></ul><ul><ul><ul><li>First trimester </li></ul></ul></ul><ul><ul><ul><li>Second trimester </li></ul></ul></ul><ul><ul><ul><li>Third trimester </li></ul></ul></ul><ul><ul><ul><li>Non pregnant </li></ul></ul></ul>
  65. 66. <ul><ul><li>All of the following are increased in pregnancy except: </li></ul></ul><ul><ul><ul><li>Renal plasma flow </li></ul></ul></ul><ul><ul><ul><li>GFR </li></ul></ul></ul><ul><ul><ul><li>Serum creatinine </li></ul></ul></ul><ul><ul><ul><li>Tubular sodium resorption </li></ul></ul></ul>
  66. 67. CONCLUSION: <ul><ul><li>Understanding maternal physiology is crucial in understanding the changes associated in pregnancy </li></ul></ul>
  67. 68. CONCLUSION: <ul><ul><li>This knowledge will help us distinguish the physiologic and pathologic processes during pregnancy </li></ul></ul><ul><ul><li>This knowledge is also necessary to improve patient education about pregnancy </li></ul></ul>
  68. 69. For More Information and Other Maternal-Fetal Lectures, Please Visit: http://maternalfetalmedicineblog.com http://onyeije.net/present http://preeclampsiaonline.net

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