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Normal Adaptation in Pregnancy Biophysical Changes


Normal Adaptation in Pregnancy Biophysical Changes Linea Nigra & Striae Gravidarum Chloasma of Pregnancy Chloasma-- mask of pregnancy is the blotchy ... – PowerPoint PPT presentation

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Title: Normal Adaptation in Pregnancy Biophysical Changes

Normal Adaptation in Pregnancy Biophysical Changes
Reproductive Organs
  • Uterus changes from an organ that is
    4 X 6.5 X 2.5cm non pregnant to 24 X
    32 X 22cm at 40 wks gestation.
  • Enlargement results from hyperplasia hypertropy
    of uterine muscle fibers and fibroelastic tissue
  • Muscle thickens early in pregnancy and thins out
    later as it enlarges 2ndary to estrogen
  • Fundus should be at level of umbilicus _at_ 20wks

Reproductive Organs
  • Cervix changes are controlled by estrogen
  • Endocervical cells secrete thick mucus plug to
    protect fetus from invading bacteria
  • Goodells Sign softening of the cx after 6wks
    gestation caused by ? vascularization, sl.
    hypertrophy hyperplasia. Cx is gt friable
  • Chadwicks Sign bluish coloration of cx vagina
    due to ? vascularization

Reproductive Organs
  • Ovaries early in pregnancy is a source of
    hormone production. Estrogen Progesterone are
    produced by corpus luteum until placenta takes
    over in 2nd trimester. Then they are less active

Reproductive Organs
  • Vagina-- ? vascularization epithelial
    hypertrophy due to estrogen gives bluish color
    called Chadwicks Sign.
  • Leukorrhea-- ? vaginal discharge is white to sl.
    gray but non-pruritic and not blood-stained.
  • Vaginal pH in pregnancy, the vaginal pH goes ?
    due to lactic acid production predisposing the
    pregnant woman to vaginal infections especially
    candida albicans (yeast)

Reproductive Organs
  • Breasts-- ? estrogen progesterone levels assist
    in preparing breasts for lactation, allowing
    growth of mammary glands and breast enlargement,
    but oxytocin and prolactin are suppressed by high
    levels of E P until time of delivery
  • ? sensitivity, tingling, tenderness are common
    sx early in pregnancy
  • ? pigmentation of areola is normal
  • Colostrum may be expressed as early as 16wks

Posture in pregnancy
  • Abdominal distention gives pelvis a forward tilt
  • ? abdominal muscle tone
  • ? weight bearing These 3 factors require a
    realignment of spinal curvature late in

Posture (contd)
  • Lordosis develops, walking is more difficult
  • Hormone, Relaxin, causes hypermobility of joints
    leading to waddling gait. Relaxin helps the
    pelvis to be more flexible during delivery of
  • Diastisis recti develops with enlarging uterus
    and may persist after delivery.

Metabolic Changes
  • Generally, basal metabolic rate (BMR)increases
    throughout pregnancy with increasing needs of the
  • ? by 15 20 by term
  • ? perspiration helps dissipate heat produced by ?
    BMR. Some moms experience heat intolerance.

Respiratory system changes
  • Maternal O2 requirements ? in response to ?
    metabolic needs, need to add to uterine muscle
    and breasts, and fetal demands.
  • ? estrogen levels relaxes rib cage allowing ?
    chest expansion
  • Diaphragm may be displaced by 4cm during pregnancy

Respiratory system changes
  • Respiratory Rate Unchanged or slightly
  • Total lung capacity-- Unchanged to slightly
  • Upper respiratory system is more vascularized and
    sx of nasal sinus congestion, epistaxis, and
    ear fullness may occur.

Normal Variations in Vital Signs
  • Blood Volume increases by 1500 ml. Or 40-50
    above nonpregnancy levels
  • Heart rate generally increases by 10-15
    beats/min by the 20th week gestation and remains
    to term.
  • Increases in heart volume and cardiac output make
    splitting S1 and S2 and S3 more audible after 20
    wks. Gestation
  • Cardiac Output Increases by 30 50

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Circulatory Changes in Pregnancy
Normal Variations in Vital Signs
  • BP remains the same during the 1st trimester. In
    the 2nd trimester, BP decreases by 5-10 in both
    systolic and diastolic due normal peripheral
    vasodilation caused by hormone changes. In the
    3rd trimester, BP returns to 1st trimester
  • Peripheral vasodilation keeps BP WNL despite the
    increased blood volume in healthy mom.

Normal Variations in Vital Signs
  • Physiologic anemia occurs because blood volume
    increases more rapidly than RBC production
  • Normal Hgb (12-16 g/dl) Hct (37-47) If Hgb
    falls lt 11g or Hct lt 34, mom is anemic. (see
    Appendix C pp. 1308-1309 for lab values in
    pregnant and non-pregnant women) 
  • RBC mass ? by 30-33 by term if an iron
    supplement is taken.

Normal Variations
  • WBC Normal non-pregnant
    5-10,000 /mm3 Normal in pregnancy
    5 15,000/mm3
  • Predominant WBCs are Granulocytes (PMNs or
    Neutrophils) Normal non-pregnant 55
    75 Normal in pregnancy 60 85
  • Lymphocytes remain basically the same throughout

Inferior Vena Cava Syndrome (IVCS)
  • Caused by the enlarging fetus resting on the
    mothers vena cava when in the supine position
    and this ? cardiac return. B/P may drop by 30mm
    Hg resulting in maternal bradycardia and feeling
    of dizziness and fainting.
  • Keep mom in a lateral recumbent position or
    tilt for all obstetric procedures
    (eg.ultrasound, amniocentesis, NST, CST etc.)

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Normal Variations
  • Renal Changes
  • Bladder capacity Increased to 1500 ml
  • Glomerular Filtration Rate(GFR)-- Increased
  • Renal Plasma Flow- Increased 30
  • Urinary frequency, urgency, nocturia (without
    dysuria) are common sx early late in pg.

Why are bladder infections common in pregnancy?
  • Urinary stasis or stagnation due to anatomical
    changes in pregnancy.
  • ? nutrients including glucose, tend to ? urine
    pH which in turn provides a medium conducive to
    bacterial growth. UTI is one of the most
    common causes of Preterm Labor and must be
    treated aggressively when sx occur.
  • Important to teach mom sx of urgency, dysuria, ?
    frequency, flank pain, and contractions.

Fluid Retentionwhy??
  • Because of Na and H2O retention, dependent edema
    is common.
  • Because of pressure of fetus on lower pelvic
    blood vessels, dependent edema is common.
  • Lateral recumbent position best facilitates
    kidney perfusion to allow for excretion of excess

Normal Variations
  • Lab ValuesSERUM
  • BUN Decreased (normal 8-20mg/dl)
  • Creatinine Decreased(normal 0.6-2mg/dl)
  • Uric Acid Decreased 1st 2nd
    trimesters (normal 4.5-5.8 mg/dl) Returns
    to nml in 3rd trimester

Normal Variations
  • Lab Values URINE
  • Glucose Present in urine of 20 of pregnant
    women (normal 0-20 mg/dl)
  • Protein Usually not present, however
    increased amino acids may spill over
    from kidneys during pregnancy.
    Trace to 1 protein are acceptable.

GI System
  • Appetite- Early in pregnancy, many women
    experience nausea and vomiting beginning around
    the 4-6th week and ending around the 14th week.
  • Morning sickness is nausea without vomiting. Hcg
    has been linked as an etiologic factor.
  • Later in pregancy, appetite? secondary to ?
    metabolic needs.

  • If vomiting persists, or is accompanied by pain,
    fever or weight loss, medical intervention is
  • Mouth - ptyalism (excessive salivation)is common
    in preganancy
  • gums often bleed secondary to ? vascularity
  • Stomach Intestines
  • pyrosis (acid indigestion or heart burn) is
    caused by ? progesterone production which causes
    the tone and motility of smooth muscles to be ?,
    leading to esophageal regurgitaion, ? gastric
    emptying and reverse peristalsis.

  • Constipation is common secondary to progesterone
    effects on GI motility and ? H2O reabsorption
    from the colon, displacement of the intestine by
    the uterus, ? activity levels.
  • Hypercholesterolemia- secondary to progesterone
    is expected and may cause gallstones as well as ?
    emptying time of the gall bladder and thickening
    of bile in pregnancy.

Endocrine Changes
  • Placenta-- Main source of hormones needed to
    sustain the pregnancy.
  • Early pregnancy-- the Chorionic Villi secrete
    HcgHuman Chorionic Gonadotropin, which prolongs
    the life of the corpus luteum. HpL-- Human
    Placental Lactogen influences cellular growth in
    the fetus and helps prepare breasts for
  • After 2nd Month of Pregnancy-- The placenta
    becomes the primary source of Estrogen and

  • Estrogen promotes enlargement of the genitals,
    uterus, and breastsstimulates growth of
    glandular tissues, ducts, alveoli, and nipples.
  • Progesterone inhibits spontaneous uterine
    contractions, develops lobes and alveoli in the
    breast for lactation, ? GI motility 

Pituitary Gland
  • Anterior lobe--gonadotropin activity (LH FSH)
    is turned off by the hormonal activity of the
    PLACENTA. Prolactin is produced in this lobe but
    ? levels of progesterone and estrogen inhibit by
    blocking the binding of prolactin to breast
  • Posterior lobe-- Oxytocin is produced but ?
    levels of Progesterone and Estrogen during
    pregnancy inhibit its effect on the uterus

  • Thyroid-- Gland activity and hormone production
    ? during pregnancy. T4 ? T3 ? 
  • Adrenals--
  • ? production of Cortisol
  • ? Aldosterone secretion which leads to ? Na and
    H2O retention  
  • Ovaries--generally quiet

IX. Immunological changes--
  • Placenta acts as interface between mother and
    fetus thus diminishing maternal response to
    antigenic fetus. Plasma proteins and steroid
    produced by the placenta alter maternal immune
    response predisposes moms to URI. 
  • IgG-- only maternal immunoglobulin to cross the
    placenta. Provides passive immunity to fetus.
  • IgA-- maternal immunoglobulin in colostrum which
    ? GI immunity to breastfed babies

Integumentary Changes
  • ? levels of Progesterone and Estrogen cause the
    release of melanotropin which leads to pigment
    changes in the skin.
  • Striae gravidarum--stretch marks caused by ?
    connective tissue strength secondary to ? adrenal
    cortisol levels
  • Linea nigra-- vertical abdominal line extending
    from the symphysis pubis to the top of the
    fundus. Does not develop in all women.

Linea Nigra Striae Gravidarum
Chloasma of Pregnancy
  • Chloasma-- mask of pregnancy is the blotchy,
    brownish hyperpigmentation of the skin over the
    cheeks, nose, and forehead, especially in
    dark-complexioned, pregnant women. Occurs only in
    50-70 of pregnant women and usually fades after
    birth. Darkening of the nipples, areola,
    axillae, and vulva occurs at the same time.
  • Telangiectasias-- vascular spiders are tiny,
    star-shaped sl. raised and pulsating
    end-arterioles secondary to ? estrogen levels.
    Noted on the neck, thorax, face and arms.
  • Occur in 65 of white women 10 of black
    women and disappear after birth.

  • Sebaceous glands and sweat glands-- Hyperactive
    during pregnancy which predisposes mom to ?
    pimples/ acne, ? perspiration due to ? blood
    supply to the skin
  • Hirsuitism-- ? growth of hair is a common sx, or
    a change in the texture of the hair. Some women
    find hair to be thickest during pregnancy and
    then experience great hair loss after birth.
    Usually, self-limiting when hormones return to

  • Do your best to understand these normal changes
    in pregnancy so that you can better understand
    the complications of pregnancy coming up next!