Maternal Adaptation in Pregnancy Notes

Maternal Adaptation in Pregnancy

Metabolic System Changes in Pregnancy

  • Anabolic State: Pregnancy is characterized by an anabolic state.

  • Basal Metabolic Rate (BMR):

    • Increases by 10-20% during pregnancy.

  • Oxygen Consumption:

    • Increases by 20% during pregnancy.

    • Increases by 40-60% during lactation.

Calcium Metabolism

  • Calcium Forms:

    • Ionized Calcium: Remains normal during pregnancy.

    • Non-ionized Calcium: Decreases during pregnancy, leading to an overall decrease in calcium levels.

  • Fetal Dependency:

    • The fetus depends on the mother for glucose, calcium, and thyroxine.

  • Hormonal Changes:

    • Vitamin D levels increase to enhance calcium absorption.

    • Calcitonin levels increase.

    • Parathyroid hormone (PTH) levels:

      • Decrease in early trimesters.

      • Increase in late trimesters.

  • Vitamin D Requirement:

    • 10 micrograms (400 international units) per day.

  • Calcium Requirement:

    • Increases to 1200 milligrams per day.

Carbohydrate Metabolism

  • Insulin Resistance:

    • Pregnancy induces insulin resistance to ensure glucose availability for the fetus.

    • Hormonal Influence:

      • Human placental lactogen (HPL) is the primary hormone responsible.

      • Estrogen, progesterone, and cortisol also contribute.

    • Maximum insulin resistance occurs between 24-28 weeks of pregnancy.

  • Diabetogenic State:

    • Pregnancy is considered a diabetogenic state due to insulin resistance, potentially leading to gestational diabetes.

  • Glucose Transport:

    • Glucose is transported to the fetus via facilitated diffusion using GLUT3 and GLUT1 transporters.

  • Glucose Level Fluctuations:

    • Fasting State: Hypoglycemia occurs as the fetus consumes maternal glucose.

    • Postprandial State: Hyperglycemia occurs due to insulin resistance.

  • Fasting Advice:

    • Pregnant women should avoid fasting to maintain stable glucose levels for the fetus.

  • Insulin Secretion:

    • Despite insulin resistance, insulin secretion increases during pregnancy.

  • Glycosuria:

    • Glycosuria is physiological during pregnancy.

    • Urine glucose levels are not reliable for diagnosing diabetes in pregnancy.

  • Proteinuria and Lactourea:

    • Proteinuria is always abnormal and may indicate pregnancy-induced hypertension (PIH).

    • Lactourea is physiological during breastfeeding.

Skin Changes in Pregnancy

  • Hormonal Influence: Skin changes are primarily due to increased estrogen, except for basal body temperature which is influenced by progesterone.

  • Linea Nigra:

    • A blue-black line extending from the xiphisternum to the pubic symphysis.

    • Caused by increased melanocyte-stimulating hormone due to increased estrogen.

  • Striae Gravidarum:

    • Stretch marks.

    • Pink during the current pregnancy.

    • Silvery white in previous pregnancies (striae albicans).

  • Chloasma Gravidarum:

    • Hyperpigmentation on the cheek area, also known as the pregnancy mask.

    • Caused by increased estrogen and resolves after delivery.

  • Spider Angioma (Spider Nevi):

    • Dilated capillaries visible on the skin surface.

    • Due to increased estrogen.

  • Palmar Erythema:

    • Redness on the palms.

    • Due to increased estrogen.

  • Basal Body Temperature:

    • Increased due to the thermogenic effects of progesterone.

Breast Changes During Pregnancy

  • Size and Weight Increase:

    • Increase in fat due to insulin.

    • Increase in alveoli primarily due to progesterone, with contributions from estrogen and prolactin.

    • Increase in ducts due to estrogen.

  • Hyperpigmentation:

    • Nipples become hyperpigmented.

    • Appearance of secondary areola.

  • Montgomery Tubercles:

    • Modified sebaceous glands on the breast.

  • Colostrum:

    • A thick, sticky, yellowish fluid present as early as 12 weeks.

    • Rich in immunoglobulins and vitamins and should be given to the neonate.

    • Composition Compared to Breast Milk:

      • Higher Concentrations: Most components are more concentrated in colostrum.

      • Lower Concentrations: Potassium (K), Fat (F), and Carbohydrates (C) are less concentrated in colostrum (KFC).

  • Breast Milk:

    • A good source of nutrients and micronutrients.

    • Deficiencies: Lacks vitamin K; low in vitamin D.

  • Milk Ejection (Galactokinesis):

    • Oxytocin is responsible. It causes contraction of myoepithelial cells in the alveoli.

  • Continuous Milk Production (Galactopoiesis):

    • Prolactin is needed.

    • Suckling of the breast by the neonate is essential.

Prolactin in Pregnancy

  • Prolactin Levels:

    • Begin to rise in the first trimester and continue to rise throughout pregnancy.

    • Maximum levels are seen during labor.

    • Levels decrease postpartum.

    • Irregular levels during lactation, depending on suckling.

  • Prolactin Influences:

    • Estrogen:

      • Increases prolactin production by positively affecting lactotrophs.

      • Keeps a check on prolactin's activity, preventing maximum milk production during pregnancy.

    • Dopamine:

      • A prolactin-inhibiting hormone.

  • Clinical Applications:

    • Low Milk Production: Administer metoclopramide (an antidopaminergic drug) to increase prolactin levels.

    • Stopping Lactation (e.g., in cases of intrauterine fetal demise): Administer dopaminergic drugs like cabergoline, bromocriptine, or pyridoxine (which converts to dopamine). High doses of estrogen can theoretically be used, but this is not recommended due to the risk of increased clotting factors and DVT.

    • Breast Engorgement: Advise breast pumps and address milk ejection problems by ensuring proper oxytocin release.

Vagina and Cervix Changes During Pregnancy

  • Vaginal Changes:

    • Chadwick's Sign: Bluish discoloration.

    • Vaginal pH: Decreases due to increased Doderlein bacteria (lactobacilli) which convert glycogen to lactic acid.

  • Cervical Changes:

    • Cervical Mucus Plug: Thick secretions close the cervix.

    • Show: The mucus plug along with some bleeding released during labor when the cervix dilates.

  • Defense Mechanisms: These changes are natural defense mechanisms against infection, preventing preterm labor.

  • Pathogenic Bacteria: Most pathogenic organisms decrease due to the acidic environment, except for Candida.

  • Common Vaginitis: Candidiasis is the most common vaginitis during pregnancy.

Uterus Changes During Pregnancy

  • Size and Weight:

    • Weight: Increases from 50-80 grams in a non-pregnant state to 1100 grams.

    • Length: Increases from 7.5 cm to 35 cm.

    • Volume: Increases from 5-10 mL to 5 liters (up to 20 liters in twin/triplet pregnancies or polyhydramnios).

  • Shape:

    • Changes from pear-shaped (pyriform) to globular, then spherical, and finally ovoid.

  • Braxton Hicks Contractions:

    • Sporadic, infrequent, and generally painless contractions, with an intrauterine pressure of 5−255-25 mmHg.

    • Near term, they become more frequent and painful, transitioning to false labor pains.

  • Dextrorotation:

    • The uterus tilts towards the right side due to the sigmoid colon on the left.

Hematological System Changes During Pregnancy

Increased Parameters

  • Blood Volume: Increases.

  • Plasma Volume: Increases (40-50%).

  • RBC Volume: Increases (20-30%).

  • Placental Perfusion: Increases due to hemodilution.

  • Hemoglobin Mass: Increases (measured in grams).

  • Oxygen Carrying Capacity: Increases.

  • Erythropoietin Levels: Increase.

  • WBC Count: Increases (up to 15,000 cells/mm³ in pregnancy, and up to 25,000 cells/mm³ postpartum).

  • Neutrophils: Increase.

  • Lymphocytes: Increase.

  • T Lymphocytes: Increase.

  • Globulins: Increase (due to estrogen).

  • Sex Hormone Binding Globulin & Thyroid Binding Globulin: Increase

  • All inflammatory markers: (CRP, ESR, Leukocyte Alkaline Phosphatase, Complement C3/C4) Increase

  • Humoral Immunity: Increases.

  • T Helper Cells 2: Increase.

  • Interleukin 4, 10, 13: Increase.

  • All Clotting Factors: Increase (except factors 11 and 13).

Decreased Parameters

  • Non-ionized Calcium: Decreases.

  • Hemoglobin Concentration: Decreases (grams/dL).

  • Viscosity of Blood: Decreases due to hemodilution.

  • Hematocrit (Packed Cell Volume): Decreases.

  • Platelet Count: Decreases (but remains within normal range - benign gestational thrombocytopenia).

  • Eosinophils: Decreases.

  • Plasma Protein Concentration: Decreases (grams/dL).

  • Albumin: Decreases.

  • Factor 11 & 13: Decreases

  • Cell Mediated Immunity: Decreases.

  • T Helper Cells 1: Decreases.

  • Interleukin 2, Tumor Necrosis Factor, Interferon Alpha: Decrease.

Unchanged Parameters

  • B Lymphocytes

  • CD4:CD8 Count

  • Bleeding Time & Clotting Time

  • Antithrombin Time

Key Concepts

  • Hemodilution: Increase in plasma volume is greater than the increase in RBC volume, leading to hemodilution and physiological anemia.

  • Physiological Anemia: Hemoglobin concentration decreases, but should not fall below 11 g/dL.

  • Hypercoagulable State: Pregnancy is a hypercoagulable state; all clotting factors increase except factors 11 and 13.

  • Fibrinolytic Activity and Anticoagulants: Decrease during pregnancy.

  • Immune Status: Pregnancy is an immunodeficient state.

  • Shift in T Helper Cells: There is a shift from T helper cells 1 to T helper cells 2 in normal pregnancy.

Respiratory System Changes During Pregnancy

Numerical Values to Memorize

  • 2: Transverse diameter of the chest increases by 2 cm.

  • 4: Diaphragm is pushed up by 4 cm.

  • 6: Circumference of the chest increases by 6 cm.

  • Subcostal Angle: Increases from 68 degrees to 103 degrees.

Increased Parameters

  • Inspiratory Capacity

  • Tidal Volume

  • Minute Ventilation

Decreased Parameters

  • Residual Volume

  • Expiratory Reserve Volume

  • Functional Residual Capacity

  • Total Lung Capacity (Slightly)

  • Blood CO2 levels

  • Arteriovenous oxygen gradient

Unchanged Parameters

  • Inspiratory Reserve Volume

  • Respiratory Rate

  • Vital Capacity

  • Blood pH

Key Concepts

  • IC, TV, and Movie: Inspiratory capacity, tidal volume, and minute ventilation increase.

  • IRV: Inspiratory reserve volume, respiratory rate, and vital capacity remain unchanged.

  • Respiratory Alkalosis: Blood carbon dioxide levels decrease.

  • Metabolic Acidosis: Compensatory; kidneys excrete more bicarbonate.

  • Oxygen Levels: Blood oxygen levels increase.

  • Bohr's Effect: Increased oxygen binding to blood.

Gastrointestinal (GI) System Changes During Pregnancy

  • Progesterone Effects:

    • Lower Esophageal Sphincter Relaxation: Increased GI reflux.

    • Gallbladder Motility: Decreased.

    • GI Motility: Normal in the antenatal period, decreased during labor.

  • Estrogen Effects: Increased chances of gallstone formation.

  • Vomiting of Pregnancy (Morning Sickness):

    • Physiological; primarily due to HCG.

    • Occurs in the first trimester, usually resolving by 16-20 weeks.

    • More common in primigravida females.

    • More intolerant to liquids.

    • Management: Small, frequent meals (e.g., Parle-G biscuits before getting out of bed), doxylamine and pyridoxine at bedtime.

  • Hyperemesis Gravidarum:

    • Excessive vomiting; not physiological.

    • Diagnosis: Weight loss >5% of pre-pregnancy weight, ketosis, or unstable vitals.

    • Causes: Excessive HCG (twin pregnancy, molar pregnancy, Down syndrome, Rh-negative pregnancy), estrogen, and progesterone.

    • Clinical Features: Metabolic alkalosis, hypokalemia, ketosis.

    • Vitamin Deficiencies: Thiamine deficiency (Wernicke's encephalopathy), vitamin K deficiency.

    • Scoring Systems: PUQE (puke) score, Rhodes index.

    • Management: Hospitalization, NPO, IV fluids, antihistamines (promethazine or prochlorperazine), dopamine antagonists (metoclopramide), ondansetron (as a last resort).

Renal System Changes During Pregnancy

  • Anatomical Changes:

    • Kidney Size: Increases by 1 cm.

    • Hydroureter: Bilateral due to progesterone.

      • More pronounced on the right side due to dextrorotation of the uterus.

    • Bladder: Mucosa is congested due to estrogen.

      • Bladder pressure increases; urethral pressure increases to maintain continence.

  • Physiological Changes:

    • Renal Blood Flow: Increases due to increased blood volume.

    • Glomerular Filtration Rate (GFR): Increases.

      • Serum Urea, Uric Acid, and Creatinine: Decrease.

  • PIH (Pregnancy-Induced Hypertension):

    • Most Common Organ Involved: Kidney.

    • GFR: Decreases due to increased blood pressure (pressure and volume are inversely related).

  • UTI (Urinary Tract Infection):

    • Most Common Cause: E. Coli.

    • Asymptomatic Bacteriuria: Increased bacteria in urine without symptoms; can lead to preterm labor and pyelonephritis and should be treated.

      • Drug of Choice: Nitrofurantoin (100 mg BID for three days or 100 mg at bedtime for ten days).

      • Recurrence Rate: 30%.

      • Recurrent Asymptomatic Bacteriuria: Nitrofurantoin 100mg at bedtime for 21 days.

  • Antibiotics Safe To Use In Pregnancy:

    • Amoxicillin

    • Ampicillin

    • Cephalosporin

    • Levofloxacin

    • Ciprofloxacin

Endocrine Gland Changes During Pregnancy

Adrenal Glands

  • Increased: All adrenal hormones, including aldosterone, except DHEA sulfate.

  • Decreased: DHEA sulfate.

Pancreas

  • Increased: Insulin secretion.

Pituitary Gland

  • Size and Weight: Increase by 125%, more in the anterior pituitary gland.

  • Sheehan's Syndrome: Necrosis of the anterior pituitary gland due to postpartum hemorrhage (PPH).

  • Hormone Changes:

    • Increased: Growth hormone, prolactin, ACTH, oxytocin (increase in late third trimester).

    • Unchanged: Antidiuretic hormone.

    • Decreased: LH (due to increased progesterone), FSH (due to increased estrogen), TSH (but remains within normal range).

  • Thyroid Changes:
    * Most Common Cause of Hypothyroidism:
    * Developing Countries = Iodine Deficiency
    * Developed Countires = Hashimoto's Thyroiditis
    * Most Common Cause of Hyperthyroidism: Graves' Disease
    * Most Common Cause of Post Partum Thyroiditis: Anti-Microsomal Antibodies,