Maternal Physiology Lecture
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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

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

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Maternal Physiology Lecture Maternal Physiology Lecture Presentation Transcript

  • MATERNAL PHYSIOLOGY
      • Chukwuma I. Onyeije, M.D.
      • Atlanta Perinatal Associates
      • Clinical Assoc. Professor
      • Morehouse School of Medicine
      • http://maternalfetalmedicineblog.com
      • http://onyeije.net/present
  • Objectives
    • Detail normal physiologic changes in the following maternal systems:
      • Cardiovascular
      • Respiratory
      • Renal
      • Hematologic
      • Gastrointestinal
      • Reproductive systems.
    • Describe the implications for these changes for normal and abnormal pregnancies.
  • Objectives
    • Review nutritional requirements normal pregnancy
    • Review components and reasons for the medical evaluation at the first prenatal visit
    • Give the reason for routine laboratory tests obtained early in pregnancy.
  • BULLET POINTS:
      • Dilutional anemia of pregnancy:
      • Lower hematocrit due to expansion of plasma volume which is greater than the increase in red blood cell mass
  • BULLET POINTS:
      • Pregnancy is a Hypercoagulable state:
      • Increased risk for venous clotting episodes
  • BULLET POINTS:
      • Hegar's sign:
      • Cervix appears bluish and engorged
  • BULLET POINTS:
      • MSAFP
      • (Maternal serum
      • alpha-fetoprotein)‏
      • Screening test of maternal blood done in the early second trimester to screen pregnant women for fetal anomalies and chromosomal abnormalities
  • BULLET POINTS:
      • Bacterial vaginosis:
      • Bacterial infection of the vagina associated with preterm labor and birth
  • BULLET POINTS:
      • Rhogam:
      • An antibody preparation of anti-Rh factor given to Rh negative women to prevent Rh isoimmunization
  • BULLET POINTS:
      • Neural tube defect (NTD):
      • An abnormality in closure of the neural tube, resulting in a spectrum of anomalies from anencephaly (no cranium or cerebrum) to spina bifida
  • BULLET POINTS:
      • Intrauterine growth restriction (IUGR): pathological condition of abnormal placentation resulting in an undergrown fetus
      • Small-for-gestational age (SGA): the lower 10% of birthweights
  • BULLET POINTS:
      • Large-for-gestational age (LGA): the upper 10% of birthweights
      • Macrosomia: an abnormally large infant (usually > 4000 gm)
  • 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.
  • The vast majority of pregnancies are uncomplicated. Excessive intervention during pregnancy can result in less than optimal outcome
  • THE CARDIOVASCULAR SYSTEM:
  • THE CARDIOVASCULAR SYSTEM:
    • Cardiac output increases 30-50%
    • Stroke volume increases about 10- 15%
    • Pulse increases about 15-20 bpm
    • Systolic ejection murmur and S3 gallop are seen in 90% of pregnant women
  • CARDIAC OUTPUT DURING PREGNANCY
  • Peripheral vascular resistance falls Blood pressure falls during the second trimester and then returns to normal during the third trimester
  • 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).
  • THE RESPIRATORY SYSTEM:
  • Lung volumes changes in pregnancy
  • NO CHANGE: Respiratory rate, Vital capacity, Inspiratory reserve volume
  • DECREASED: Functional residual capacity Expiratory reserve volume Residual volume Total lung capacity
  • INCREASED: Inspiratory capacity Tidal volume
  • BLOOD GASES: CLINICAL SIGNIFICANCE: The normal pregnant woman has a compensated respiratory alkalosis and a diminished pulmonary reserve.
  • THE RENAL SYSTEM:
  • ANATOMIC RENAL CHANGES: Kidneys increase in size and weight, Dilatation of ureters (R > L) Bladder becomes an intra-abdominal organ
  • HEMODYNAMIC RENAL CHANGES: GFR increases 50%, Renal plasma flow increases by 75% Creatinine clearance increases to 150-200 cc/min
  • METABOLIC RENAL CHANGES
      • BUN and serum creatinine decrease by 25% Increase in tubular reabsorption of sodium
      • Increase in glucose excretion
  • METABOLIC RENAL CHANGES
      • Plasma osmolarity decreases about 10 mOsm/kg H2O
      • Marked increase in renin and angiotensin levels, BUT markedly reduced vascular sensitivity to their hypertensive effects
  • CLINICAL SIGNIFICANCE of RENAL CHANGES
      • :
      • Pregnant women are at increased risk for prone to pyelonephritis
      • Pregnant women are at increased risk for bladder rupture during abdominal trauma.
  • THE HEMATOLOGIC SYSTEM
  • Plasma volume and RBC mass Plasma volume increases by about 50% RBC volume increases by about 30%
  • Plasma volume and RBC mass END RESULT: ”Dilutional anemia of pregnancy", Average hemoglobin during pregnancy is 11.5 g/dl
  • Plasma volume and RBC mass
  • OTHER HEMATOLOGIC CHANGES: WBC count increases Platelet count decreases, but stays within normal limits
  • COAGULATION SYSTEM: Pregnancy is a "hypercoagulable state" Increased levels of fibrinogen, factor VII-X The placenta produces a plasminogen activator inhibitor
  • 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.
  • THE GASTROINTESTINAL AND REPRODUCTIVE SYSTEMS
  • Gastrointestinal System Decreased motility, due to influence of progesterone Reduced gastric acid secretion
  • 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.
  • 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
  • NUTRITIONAL CONSIDERATIONS DURING PREGNANCY
  • 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
  • Average weight gain THERE IS NO SUCH THING AS “OPTIMAL” WEIGHT GAIN Normal BMI: 20 lbs Underweight BMI: 30 lbs Overweight BMI 16 lbs
  • 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
  • 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
  • The pregnant patient is best served by having a healthy balanced diet with iron and folate supplementation. Only rarely are other vitamin supplements necessary
  • PRENATAL CARE
  • The first prenatal visit Decide: Is this patient normal or high-risk?
  •  
  • COMMON COMPLAINTS OF PREGNANCY
  • Nausea and vomiting: usually dissipates by 15 weeks
  • Constipation: common throughout pregnancy
  • Heartburn: often worsens as pregnancy progresses
  • Vaginitis: treat only if symptomatic
  • Varicose veins: treat symptomatically
  • Headaches
  • Lower extremity edema is very common
  • Backache: Lordosis is common with change in the center of gravity
  • Faintness and light-headedness
  • Carpal tunnel syndrome
  • REVIEW QUESTIONS:
      • Which of the following INCREASES in pregnancy?
        • FRC
        • ERV
        • RV
        • TV
      • During which of the following states is the blood pressure lowest?
        • First trimester
        • Second trimester
        • Third trimester
        • Non pregnant
      • All of the following are increased in pregnancy except:
        • Renal plasma flow
        • GFR
        • Serum creatinine
        • Tubular sodium resorption
  • CONCLUSION:
      • Understanding maternal physiology is crucial in understanding the changes associated in pregnancy
  • CONCLUSION:
      • This knowledge will help us distinguish the physiologic and pathologic processes during pregnancy
      • This knowledge is also necessary to improve patient education about pregnancy
  • For More Information and Other Maternal-Fetal Lectures, Please Visit: http://maternalfetalmedicineblog.com http://onyeije.net/present http://preeclampsiaonline.net