maternal adaptations

MATERNAL ADAPTATION DURING PREGNANCY

Overview

  • Maternal adaptation refers to the physiological changes a woman's body undergoes during pregnancy to support the developing fetus.

  • Changes occur in various systems including gastrointestinal, respiratory, cardiovascular, urinary, endocrine, and breast.

Other Changes

  • Gastrointestinal System

  • Pregnancy Respiratory System

  • Cardiovascular System

  • Breasts

  • Urinary System

  • Endocrine System

  • Abdomen

SIGNS AND SYMPTOMS OF PREGNANCY

Presumptive Signs (Subjective)

  • Amenorrhea: Absence of menstruation.

  • Fatigue: Increased tiredness.

  • Breast Changes: Enlargement and tenderness.

  • Frequent Urination: Increased urinary frequency.

  • Quickening: Perception of fetal movement.

  • Emesis and Nausea: Commonly referred to as morning sickness.

Probable Signs (Objective)

  • Positive Pregnancy Test: Indicates the presence of hCG (human chorionic gonadotropin).

  • Ballottement: The returning of the fetus when the uterus is pushed with fingers.

  • Fetal Outline Palpation: Detection of fetus through palpation.

  • Braxton Hicks Contractions: Intermittent contractions that may occur as the body prepares for labor.

  • Goodell’s Sign: Softening of the cervix noticeable around 5 weeks.

  • Chadwick’s Sign: Bluish color of the vulva, vagina, and cervix indicating increased blood flow, typically around 6-8 weeks.

  • Hegar’s Sign: Softening of the lower uterine segment around 6-12 weeks.

  • Enlarged Uterus: Growth of the uterus as pregnancy progresses.

Details on Probable Signs

  • Hegar’s Sign: Softening of the lower uterine segment or isthmus, typically between 6-12 weeks.

  • Goodell’s Sign: Cervical softening occurring at about 5 weeks.

  • Chadwick’s Sign: Notable bluish-purple coloration of vaginal mucosa and cervix by 6-8 weeks.

  • Ballottement: Palpable rebound felt from the floating fetus when pressing against the cervix, generally between 16-18 weeks.

  • Positive Pregnancy Test: Confirms pregnancy with a threshold hCG level greater than 25 mlU/mL.
      - Expected doubling of hCG every 48-72 hours, peaking around day 60.
      - Low hCG levels may indicate ectopic pregnancy; high levels may relate to molar pregnancy or multiple gestations.

Positive Signs of Pregnancy

  • Ultrasound: Confirms the presence of an embryo or fetus.

  • Experienced Clinician Detection: Fetal movement felt via clinical examination.

  • Fetal Heart Tones: Detected via Doppler ultrasound.

PHYSIOLOGIC ADAPTATIONS DURING PREGNANCY

Uterine Changes

  • Capacity Increase: Ranges from approximately 10 mL to 5000 mL.

  • Weight Increase: Grows from around 70 g to 1200 g.

  • Growth Mechanisms:
      - Hyperplasia: Formation of new smooth muscle cells during the first trimester.
      - Hypertrophy: Mechanical stretching of uterine tissue by the growing fetus during the second and third trimesters.

Growth and Measurement of the Uterus (Fundal Height)

  • 12 weeks: At symphysis pubis.

  • 16 weeks: Halfway between pubis and umbilicus.

  • 20 weeks: At umbilicus.

  • 36 weeks: Near the xyphoid process.

Cervical Changes

  • Goodell Sign: Softening of the cervix occurs around 6-8 weeks.

  • Influence of Estrogen: Results in increased cervical softness.

  • Formation of Mucus Plug: Due to increased progesterone and mucus secretion, blocking the cervical os to protect against bacterial invasion.

  • Chadwick Sign: Bluish-purple discoloration of the cervix indicating increased vascular supply by 6-8 weeks.

  • Cervical Ripening: Prepares for delivery, usually around 4 weeks before birth.

Vaginal Changes

  • Vascularity: Increased due to estrogen.

  • Mucosa Thickness: Enhanced thickness of vaginal mucosa.

  • Connective Tissue Loosening: Accompanied by hypertrophy of smooth muscle and lengthening of the vaginal vault.

Leukorrhea

  • Secretions: More acidic, thick, and white.

  • Increase in Vaginal Discharge: Generally normal unless accompanied by itching or irritation.

  • Risk for Candida albicans: A fungal infection potentially transmitted to the infant as thrush, particularly significant if symptoms occur.

Ovarian Function

  • Corpus Luteum Production: Produces estrogen and progesterone until approximately week 6-7, after which the placenta assumes hormone production.

  • Ceasing Ovulation: No ovulation occurs during pregnancy.

Breast Adaptations

  • Hormonal Influence: Increased size and tenderness due to progesterone and estrogen.

  • Vascular Changes: Visible veins from increased blood flow.

  • Striae: Stretch marks occur in about 50% of women due to skin expansion.

  • Color Change: Nipples and areolas may become hyperpigmented.

  • Montgomery’s Tubercles: Prominent sebaceous glands supporting nipple lubrication during breastfeeding.

  • Colostrum Production: Initiated in the third trimester as a precursor to breast milk.

GENERAL BODY SYSTEM ADAPTATIONS

Cardiovascular System Changes

  • Increased Demand: The placenta and uterus require additional blood and oxygen.

  • Heart Enlargement: Slight enlargement due to increased workload, reversing post-delivery.

  • Heart Rate: Increases as a response to demand.

  • Blood Volume and Plasma Volume: Increases by 50% over pregnancy.

  • Cardiac Output: Elevated due to increased volume and heart rate.

  • Blood Pressure: Remains generally stable while adapting to increased flow.

  • Increased Blood Flow: Notable increase to kidneys, skin, and uterus/placenta.

Physiologic Anemia of Pregnancy

  • Dilution Effect: Occurs due to rapid plasma volume increase, leading to lower hemoglobin and hematocrit.

  • Normal H/H Levels: 12-16 g/dL hemoglobin normal; first trimester hemoglobin at least 11 g/dL; second trimester at least 11 g/dL.

  • Diet Assessment: Importance of assessing patient diet to mitigate anemia.

  • Prenatal Vitamins: Encourage under consumption of iron supplements.

Vena Cava Syndrome (Supine Hypotensive Syndrome)

  • Cause: Gravid uterus compresses the vena cava while supine, leading to decreased blood flow to the heart and possible maternal hypotension.

Blood Component Changes

  • RBC Increase: By 23-30% not proportionate to plasma volume increase.

  • WBC Increase: Rises to 12,000-16,000 from a normal baseline of 5,000-10,000.

  • Clotting Factors: Increased levels of fibrin and plasma fibrinogen, indicating a hypercoagulable state.

  • Risk for Thrombus Formation: Enhanced clotting alongside venous stasis increases thrombus risk in pregnant women.

Varicosities

  • Associated Factors: Increased venous stasis, the vasodilatory effects of progesterone, obesity, and lack of activity.

  • Treatment Options:
      - Elevate legs during rest periods.
      - Use support hose; wear low-heeled shoes.
      - Avoid crossing legs, prolonged sitting and standing.
      - Ice packs for vulvar varicosities.
      - Manage hemorrhoids through dietary changes, topical anesthetics, and cold compresses.

Respiratory System Changes

  • Tidal Volume Increase: Up to 30-40%.

  • Diaphragm Elevation: Rises about 4 cm.

  • Chest Circumference: Increases by approximately 6 cm.

  • Breathing Pattern Change: Shifts to more diaphragmatic rather than abdominal.

  • Respiratory Rate: Faster and deeper to supply oxygen efficiently to the mother and fetus.

  • Nasal Stuffiness and Epistaxis: Common issues due to higher estrogen levels.

Gastrointestinal System Changes

  • Mouth Tissues: Increased vascularity leading to bleeding gums.

  • Ptyalism: Excessive salivation, typically resolves spontaneously, managed with gum or hard candies.

  • Dental Concerns: Increased plaque can raise risks for gingivitis, periodontitis, and associated complications (e.g., preterm births).

Upper Gastrointestinal System

  • Motility Decrease: Influenced by progesterone, leading to potential risks for reflux and constipation.

  • Risk Factors: Includes low fiber intake, iron supplements, and decreased physical activity.

Lower Gastrointestinal System

  • Gallbladder Function: Prolonged emptying and increased risk for gallstones with obesity and advanced maternal age.

  • Treatment: Laparoscopic cholecystectomy is considered safe during all trimesters.

PICA (Food Cravings)

  • Description: A disorder causing unusual cravings during pregnancy; lack of identifiable cause.

  • Concerns: Associated with potential anemia, emphasizing the need for assessment and monitoring.

Renal/Urinary System Changes

  • Kidney Changes: Enlargement occurs during pregnancy.

  • Urinary Stasis: Dilation of the renal pelvis and ureters increases risks for urinary tract infections.

  • Bladder Changes: Capacity doubles, leading to increased frequency of urination.

  • GFR Increase: Glomerular filtration rate experiences a rise of 40-60%.

  • Blood Flow: Increased to kidneys by 50-80% due to heightened cardiac output.

Musculoskeletal System Changes

  • Hormonal Changes: Alter relaxation of ligaments through relaxin and progesterone.

  • Postural Adjustments: Leads to waddling gait and lordosis due to the distention of the abdomen.

  • Associated Discomforts: Commonly includes leg cramps, carpal tunnel syndrome, and backache/sciatica.

Integumentary System Changes

  • Skin Circulation: Increased blood flow leads to hyperpigmentation.

  • Specific Areas Affected: Includes nipples, areola, umbilicus, perineum, and axilla.

  • Pregnancy Mask (Chloasma): Brownish pigmentation often seen on the face.

  • Linea Nigra: A dark line extending from the umbilicus to the pubic region.

Hair and Nails

  • Hair Growth: Decrease in hair loss during pregnancy.

  • Nail Changes: Nails commonly grow faster but become thinner during this period.

ENDOCRINE SYSTEM CHANGES

Hormonal Increases

  • Thyroid Gland: Enlarges, crucial for fetal brain development.

  • Hormonal Transition: Initially hormonal support by corpus luteum; thereafter, the placenta plays a significant endocrine role producing high estrogen and progesterone levels.

Human Placental Lactogen (hPL)

  • Function: Increases insulin resistance, providing glucose necessary for fetal growth while promoting breast tissue development in preparation for lactation.

Immune System Changes

  • Immunosuppression: Pregnancy results in a suppressed immune state.

  • Vaccination Recommendations: Immunizations recommended, excluding live virus vaccines such as Rubella and Varicella, while flu and Tdap vaccines are encouraged, along with the COVID-19 vaccine.

NUTRITIONAL NEEDS OF PREGNANCY

General Guidelines

  • Diet Variety: Consume a variety of foods from each food group.

  • Meal Frequency: Recommended three meals a day plus 1-2 snacks.

  • Limitations: Reduce soda and caffeine intake.

  • Hydration: Increase water consumption.

  • Prenatal Supplements: Include iron in prenatal vitamins.

  • Avoid Diuretics: No restriction of salt intake.

  • Physical Activity: Engage in daily exercise.

Maternal Weight Gain Recommendations

  • Underweight (BMI < 18.5): 28-40 pounds.

  • Normal Weight (BMI 18.5 - 24.9): 25-35 pounds.

  • Overweight (BMI 25 - 29.9): 15-25 pounds.

  • Obese (BMI > 30): 11-20 pounds.

  • Weight Gain Distribution:
      - First Trimester: Total of 3-5 pounds.
      - Second and Third Trimesters: Approx. 1 pound per week.