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  • 1. Physiological Changes in Pregnancy
    Sandy Warner RNC OB, MSN
  • 2. Adaptations
    Nurses must understand the normal anatomical and physiological changes in pregnancy to recognize any deviation from normal.
    In addition to physical changes, there are also psychological changes that occur with pregnancy.
  • 3. Body system alterations
  • 4. Cardiovascular
    Cardiovascular adaptation affects all organ systems.
    Cardiovascular anatomy and physiology changes to accommodate increasing maternal and fetal circulatory needs.
  • 5. Heart
    Anatomic changes:
    Heart is enlarged, displaced upward and rotates to the left.
    PMI (point of maximal impulse) shifts to 4th
    intercostal space and closer to the midclavicular line.
  • 6. Heart sounds and rate:
    Audible splitting of S1 and S2; S 3 becomes audible.
    Benign systolic murmurs are common.
    Heart rate increases 15-20 beats as pregnancy progresses.
  • 7. Cardiac Output
    Defined as the amount of blood pumped from the left ventricle into the aorta each minute.
    (heart rate x stroke volume = CO)
    In pregnancy increased by 40% by 36-38 wks.
    Influenced by:
    Blood volume
    Stroke volume
    Heart rate
  • 8.
  • 9. Blood Pressure
    Due to decreased systemic vascular resistance, blood pressure is lower at end
    of 1st trimester and throughout 2nd, returning to baseline in 3rd trimester.
    Also affected by renin-angiotensin-aldosterone system from kidneys.
  • 10. Hematological Changes
    Increase in WBCs and RBCs.
    Increase blood volume for uterus, fetus and increased perfusion of other organs, especially kidneys.
    Increased plasma volume ratio to RBC volume leads to hemodilution.
  • 11. Hematological changes cont.
    Decreased fibrinolytic activity
    Platelets remain normal or might decrease slightly
    Increased need for iron related to RBCs
  • 12. Respiratory
    Anatomic changes:
    Diaphragm elevation
    Chest expansion
    Capillary dilation early in pregnancy causes
    Engorgement of entire tract from nares to bronchi
    Voice changes
  • 13. Respiratory
    Physiological changes:
    Increased need for oxygen
    Improved oxygen delivery
    Compensatory respiratory alkalosis
  • 14. Genitourinary
    Kidneys increase in size and GFR.
    Ureters dilate and elongate, becoming compressed by uterus.
    Bladder tone decreases due to progesterone, becomes displaces as uterus grows.
  • 15. Genitourinary
    Urine flow accumulates and slows.
    Increased renal excretion of BUN, creatinine and glucose.
    Decreased serum BUN, creatinine and glucose.
    Decreased tubular reabsorption of glucose.
    Increased tubular reabsoption of sodium.
  • 16. Genitourinary
    Uterus rises out of pelvis during 1st trimester.
    Weight increases from 70 gms to 1100 gms.
    Volume at term averages 5 L but may be as
    much as 20 L.
    Individual cells increase 100 fold in length by term,
    allowing for contractions and involution.
  • 17. Genitourinary
    Increases in mass and fluid content.
    85% connective tissue and 15% smooth muscle.
    Ripening occurs via softening and effacement with the influence of hormones.
  • 18. Gastrointestinal
    Mouth changes in tastes, increase in saliva production, gums swell and bleed easier.
    Esophagus decreased tone leads to reflux.
    Stomach decreased tone and motility.
    Intestines smooth muscle relaxation and
    decreased tone and motility - constipation
  • 19. Gastrointestinal
    Esophagus, stomach and intestines move as uterus grows.
    Round ligament stretches as uterus expands.
    Gallbladder decrease tone and motility
    combined with increased emptying time can
    cause increased risk of gallstones.
  • 20. Gastrointestinal
    Hyperemesis common in first trimester.
    Strong sense of smell.
    Increased saliva production.
    Can persist throughout pregnancy.
  • 21. Immunological
    Placenta functions to help protect the fetus from infection with IgG.
    Decreased Tcell activity with pregnancy that increases susceptibility to viral infections.
    Immunity is enhanced by sleep/rest and decreased stress.
  • 22. Musculoskeletal
    Abdominal muscles relax and pelvis tilts forward.
    Center of gravity shifts.
    Joints relax waddling.
    Muscle aches from increasing weight of uterus.
    Posture change due to lumbodorsal curve of spine.
  • 23. Musculoskeletal
    Normal weight gain 25-35#.
    Slight weight loss in 1st trimester from
    nausea and vomiting.
    Average 1#/wk weight gain in 2nd and 3rd trimesters.
  • 24. Endocrine
    Function increases to meet metabolic and growth needs.
    Helps regulate calcium, phosphorus, Vit. D and magnesium concentration.
    Increases in pregnancy to help skeletal growth.


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