Evelyn M. Hickson, RN, MSN, CNS, WCC

Objectives  Describe the physiological changes that occur during pregnancy.  Identify changes in the lab values that occur during pregnancy as a result of normal physiological adaptation.  Identify abnormal laboratory values for the pregnant woman and the underlying physiology.

The most obvious changes in pregnant women are physical. Fetal growth and enlargement of the uterus causes the rearrangement and compression of most abdominal organs. PhysicalChanges

 45-50% increase in blood volume and cardiac output by term This contributes to the hyper-coagulability of pregnancy and an increased risk of DVT due to increased clotting factors present in plasma.  Hypertrophy of both atria in the heart  Common to auscultate dysrthymias or murmurs  Heart rate increases 8-15 bpm above baseline

 Late in pregnancy the inferior vena cava is completely occluded in the supine position. Cardiac output is highest in lateral and knee- chest position. Prior to 24 weeks the effect of supine position is not observed.  Blood pressure Decrease occurs by 8 weeks and into the second trimester and then gradually returns to nearly pre-pregnant level by end of the third trimester.

 Non-pregnant = 35 ml/min  10 weeks = 50 ml/min  28 weeks = 125 ml/min  Term = 500 – 1000 ml/min  By the end of pregnancy 1/6 th of total maternal blood volume is contained in the vascular system of the uterus

 Kidney and ureters Dilation more prominent on right. May last up to 3 months postpartum. Increased risk of pyleonephritis.  Bladder Decreased tone and increased capacity Displaced in late pregnancy Increased risk of UTI  Renal blood flow increases 35 – 60% Increase GFR results in excretion of glucose, urea, uric acid, & calcium

 Mechanical changes Enlarging uterus pushes on diaphragm and compresses the space available for respiration  Biochemical changes Progesterone and Relaxin relaxing the smooth muscles, joints and cartilage. The physiological dyspnea results in hyperventilation, lower pCO2, and maternal respiratory alkalosis.  The lower pH facilitates the release of oxygen from mother to fetus.

 Estrogen causes increased blood flow to the mouth, making the gums friable and contributing to gingivitis. The saliva becomes more acidic.  The tone of the lower esophageal sphincter decreases due to progesterone, causing smooth muscle relaxation, increasing heartburn and reflux.

Gastrointestinal  Compression of abdominal organs and hormonal changes lead to delayed gastric and intestinal emptying and increasing flatulence.  Cholestasis and cholelithiasis of pregnancy

 Changes in pigmentation occurring in up to 90% of pregnancies Chloasma (mask of pregnancy) Linea nigra Darkening of areola, umbilicus, vulva, and perianal skin. Pigmented nevi, freckles and recent scars may deepen in color.  Sweat glands become hyperactive

Skin changes  Pruitic Urticaric Papules and Plaques of Pregnancy (PUPPS)

 Mild degrees of hirsutism are common during pregnancy.  During normal pregnancy the proportion of hair in the growth phase is increased compared to that in the rest phase. After delivery, the number of hairs entering the rest phase increase and it is normal to see a marked increase in scalp hair loss 2 to 4 months after delivery.

 The breasts begin to change early in pregnancy, with tenderness, tingling sensations, and a feeling of heaviness within 4 weeks of the last menstrual period.  The breasts rapidly enlarge with ductal growth stimulated by estrogen and alveolar hypertrophy stimulated by progesterone.  Colostrum is present as early as 16 weeks.

 Increased thickness of cornea  Decreased intraocular pressure  Common for prescriptions to change during pregnancy, sometimes for the better.

 Lordosis - Progressive increase in anterior convexity of the lumbar spine. Changes in the center of gravity occur due to the shifting of weight and growth of the fetus.  Ligaments of the pubic symphysis and sacroiliac joints loosen and those suspending the uterus lengthen during pregnancy

 Normal values for a non-pregnant adult woman Hct and Hgb  During pregnancy the lower limits of normal WeeksHgbHct

Thyroid Function TestNon-pregnant (microgram/dl) Pregnant Total T Increased Total T Increased TSH, Free T4, & Free T3Unchanged

ABG ComponentNon-pregnantPregnant pCO2 (mmHg) Bicarb (mEq/L) pH pO2 (mmHg) SaO % (unchanged) BE (mmol/L)-2 to +2 (unchanged)

ABG ComponentNon-pregnantPregnant WBC5,000-10,0005,000-15,000 Increased to 20,000 in labor RBC Hgb Hct36-46%32-36% Plt150, ,000/mm3 Unchanged until increase 3-5 days pp

ChemistryNon-pregnantPregnant Glucose mg/dl No change BUN, serum mg/dl5-12 mg/dl Creatinine, serum mg/dl mg/dl Uric acid, serum mg/dl mg/dl Sodium, serum mEq/L mEq/L Potassium, serum 3.7 to 5.2mEq/L mEq/L Chloride, serum mEq/L98-106mEq/L Calcium mg/dlDecreased 10% Total protein g/dl g/dl Albumin mg/dl g/dl Globulin-A/G ratio g/dl3-4 g/dl Bilirubin, total mg/dl No change Alk phosphatase IU/LInc until 6 wk pp CO Bicarb 22mEq/L21-30mEq/L Cholesterol <200 mg/dlUp to 300 mg/dl

Urine Non-pregnant Pregnant Protein<150 mg/dl<300 mg/dl Creatinine Clearance ml/min120/160 ml/min

American Thyroid Association. (2005). Thyroid disease and pregnancy. Retrieved February 23, 2005 from nancy_broch.pdf. Gabbe, S.G., Niebyl, J. R., Simpson, J. L., Senkarik, M., & Cooley, M. (Eds.). (2001). Obstetrics: Normal and Problem Pregnancies (4th ed.). New York: Churchill Livingston Varney, H., Kriebs, J.M. & Gegor, C. (2004). Varney's Midwifery (4th ed.). Boston: Jones and Bartlett Inturrisi, M. (ed.). (2003). Labor & Delivery In My Pocket: An Emergency Reference (2nd ed.). Mesa, AZ: In My Pocket Books, Inc. Somani, S., Bhatti, A., Ahmed, I.K. (2008). Pregnancy, Special Considerations. Retrived February 23, 2010 from