Comprehensive Prenatal & Maternal Health Notes

Pelvic Anatomy & Labor Implications

  • Four classic pelvic shapes (p. 28)

    • Gynecoid – “classic female” pelvis
      • Broad pelvic brim & wide mid-pelvis
      • Fastest, most favorable for vaginal birth.

    • Android – typical male pelvis
      • Heart-shaped inlet, narrow mid-pelvis
      • Ischial spines prominent ⇒ higher C-section rate.

    • Anthropoid – oval inlet, narrow AP diameter
      • Baby can pass, but labor often prolonged.

    • Platypelloid – flat, wide inlet, shallow cavity
      • Least favorable; vaginal birth rare unless very small pre-term fetus.

  • Critical landmark = ischial spines
    • Distance between spines predicts ability of fetal head to descend.
    • Vaginal exam in labor assesses head station relative to spines (−3 to +3).

Prenatal Visit Schedule (“4-2-1 Rule”)

  • 0!\text{–}!28\text{ wks}: visit q4 wks.

  • 29!\text{–}!36\text{ wks}: visit q2 wks.

  • 37\text{ wks→birth}: visit weekly.

  • Rationale: earlier detection of complications & timely planning for delivery.

Fetal Maturity Benchmarks

  • Age of viability (course definition) = 20\text{ wks} gestation.
    • <20 wks ⇒ products of conception are managed in ED; no neonatal resuscitation possible (lungs & other organs too immature).

  • Pre-term = 20\text{–}<37\text{ wks}.

  • Term = \ge37\text{ wks}.

  • Post-dates = >42\text{ wks} (not stressed in video but standard definition).

Key Laboratory & Screening Timeline (Table 4.1, p. 50)

FIRST TRIMESTER – Detect maternal infection & baseline status

  • Blood type, Rh factor & antibody screen.
    • Rh-neg mother + Rh-pos fetal cells ⇒ iso-immunisation risk; may need Rho(D) immune globulin.

  • CBC – anemia if Hgb<10\,\text{g/dL}.

  • TORCH panel (5 neuro-teratogenic viruses)
    • T = Toxoplasmosis
    • O = Other: hepatitis B, HIV, varicella, Zika, etc.
    • R = Rubella titer
    • C = CMV
    • H = HSV-2

  • Syphilis/VDRL – legally mandated.

  • TB screen – routine in many clinics.

  • Pap smear (cervical CA).

  • Vaginal swabs for Chlamydia & Gonorrhea.

  • Urinalysis & culture – asymptomatic bacteriuria can trigger pre-term labor.

SECOND TRIMESTER – Detect fetal metabolic risk

  • 24-28 wks: 1-hr Oral Glucose Tolerance Test (OGTT)
    • Drink 50 g glucola, draw plasma glucose @1 h.
    • Abnormal = \ge140\,\text{mg/dL}.
    • If abnormal ⇒ 3-hr OGTT (fasting + 100 g load, blood q1 h ×3).

THIRD TRIMESTER – Prevent neonatal sepsis & confirm growth

  • 35-37 wks: Group B Streptococcus (GBS) culture (vaginal & rectal).
    • Positive ⇒ IV ampicillin 1\,\text{g} q8 h from labor onset until +8\,\text{h} post-delivery.
    • Newborn vitals & full assessment q4 h ×24 h.

Rh Factor & Iso-immunisation Basics

  • Rh (Rhesus-D) antigen present in ~85 % of population.

  • Rh-neg mom exposed to Rh-pos RBCs → forms anti-D IgG.

  • Antibodies cross placenta in current or future pregnancy ⇒ hemolytic disease.

  • Screen: Type & Ab @1st visit; re-screen @28 wks & postpartum.

  • Prophylaxis: Rho(D) IG 300\,\mu g IM @28 wks & within 72 h after birth of Rh-pos infant or any bleeding event.

GTPALM Obstetric History System

  • G (Gravida) – total times uterus has been pregnant (include current, regardless of outcome or # fetuses).

  • T (Term) – births \ge37\text{ wks}. Each pregnancy = 1.

  • P (Pre-term) – births 20\text{–}<37\text{ wks}.

  • A (Abortions) – losses <20\text{ wks} (spontaneous or induced).

  • L (Living) – currently living children; multiples each counted.

  • M (Multiples) – some forms include explicit multiple count.
    Example (lecture): woman pregnant now; 1 miscarriage @8 wks; 1 birth @34 wks with surviving twins → G3\;T0\;P1\;A1\;L2.

Calculating Estimated Due Date – Nägele’s Rule

  1. Take 1st day of Last Normal Menstrual Period (LNMP).

  2. Subtract 3 months.

  3. Add 7 days.

  4. Adjust year if LNMP fell in Jan-Mar (EDD happens same calendar year).
    • Example: LNMP \text{18 Mar 2023} \Rightarrow EDD = 23 Dec 2023.

Pregnancy Confirmation – The “3 P’s” (pp. 52-55)

Presumptive (subjective)

  • Amenorrhea, N/V, breast changes, quickening, fatigue, urinary frequency, etc.

  • Can arise from non-pregnant states (athlete, PCOS, GI gas…).

Probable (objective – examiner can note)

  • Goodell’s sign – softening of cervix.

  • Chadwick’s sign – bluish-violet vaginal/cervical color.

  • Hegar’s sign – soften lower uterine segment.

  • McDonald’s sign – easy flexion uterine body ↔ cervix.

  • Braxton-Hicks contractions.

  • +Urine/serum hCG test (may indicate ectopic or mole, not necessarily viable IU pregnancy).

Positive (only 3, must be clinician-confirmed)

  • Fetal heartbeat heard (Doppler ~10 wks).

  • Fetus visualised on ultrasound.

  • Palpable fetal movement by examiner.

Physiological Adaptations & Nursing Implications

Cardiovascular

  • Blood volume ↑ 45\text{–}50\% → pseudo-anemia (dilution).

  • BP may drop mid-pregnancy, then return.

  • Supine Hypotension Syndrome
    • Uterus compresses inferior vena cava when mother lies flat.
    • S/S: dizziness, pallor, \uparrow HR.
    • Intervention: Left-side-lying; pillow under hip/abdomen.

Respiratory

  • Diaphragm elevated; mild dyspnea until “lightening” (fetal descent) late 3rd tri.

Gastro-intestinal

  • Delayed gastric emptying & sphincter relaxation ⇒ reflux/heartburn.
    • Sit upright 45\,\text{min} after meals; avoid spicy/fried food; ginger tea for nausea.

Musculoskeletal

  • Lumbar lordosis (“sway back”); waddling gait; round-ligament pain.
    • Support belt, side-lying with pillow under abdomen.

Weight Gain & Metabolic Concerns

  • Normal-BMI women: target ≈ 25\text{–}35\text{ lb}; \approx 1\text{ lb/wk} in 2nd/3rd tri.

  • Obesity (BMI \ge30) elevates risk for pre-eclampsia & GDM; ADA originally advised no gain, practical goal is minimal gain.

  • Endurance runners/vegetarians may need closer monitoring for under-gain & anemia.

Essential Maternal Nutrition (pp. 63-65)

  • Extra calories
    • 2nd tri: +340\,\text{kcal/day}
    • 3rd tri: +450\,\text{kcal/day} (brain growth surge)

  • Daily minimums
    • Protein: 60\,\text{g} high-quality (palm-size portions of meat/fish/legumes, nuts in mason jars for snacks).
    • Calcium: 1200\,\text{mg} (dairy, fortified OJ, almonds; take separately from iron).
    • Iron: 30\,\text{mg} (take a.m. on empty stomach with OJ; alt = spinach, strawberries, fortified cereal).
    • Folic Acid: 0.4\,\text{mg} (start 3\text{–}6\text{ mo} pre-conception to prevent neural-tube defects).

  • Sodium moderation (<2000\,\text{mg/day}); avoid routine fried foods (instructor’s “no French-fries” rule).

Group B Strep Prophylaxis – Protocol Details

  • Screen 35-37 wks → if positive:
    • Start ampicillin 1\,\text{g IV} q8 h at admission; continue until 8\text{ h} postpartum.
    • Neonate: vitals & assessment q4 h ×24 h for early-onset sepsis.

  • Historical context: unexplained NICU deaths traced to maternal vaginal GBS; universal screening adopted nationally.

Gestational Diabetes Overview

  • Pathophysiology: placental hormones → insulin resistance; maternal ↑ glucose crosses placenta, fetus must ↑ insulin → macrosomia.

  • OGTT thresholds (see above).

  • High-risk: obesity, age >25, prior GDM, strong family Hx, polycystic ovary syndrome.

Supine Hypotension & Labor Positioning

  • During labor, contractions already ↓ placental flow; avoid back-lying.

  • Acceptable: full lateral, semi-Fowler with wedge, hands-and-knees, birthing ball.

Patient Advocacy & Safety Pearls (Instructor Stories)

  • Persistent BP ≥200/110 warrants immediate intervention → uncontrolled pre-eclampsia can be fatal (mother & fetus).

  • Teach clients to demand assessment if “something feels wrong”; bring a knowledgeable support person; stay until satisfied with care.

  • Nurses must choose between being “good” (tasks) vs. “great” (critical advocacy & evidence-based vigilance).

Quick Reference – Common Numbers & Formulas

  • Viability: 20\,\text{wks}

  • Term: \ge37\,\text{wks}

  • Anemia: Hgb<10\,\text{g/dL}

  • OGTT abnormal: \ge140\,\text{mg/dL} @1 h

  • BP crisis example: \ge160/110\,\text{mmHg} (preeclampsia severity marker)

  • Ampicillin GBS dose: 1\,\text{g IV q8h}

  • Rho(D) IG standard dose: 300\,\mu g IM

  • Iron–calcium spacing: \ge2\,\text{h} apart

Links to Other Course Content

  • Pelvic measurements connect to mechanics of labor (next lecture).

  • TORCH agents & early ultrasound findings reviewed in “Complications of Pregnancy” week.

  • Pre-eclampsia, gestational HTN, & HELLP syndrome handled in detail in high-risk OB unit.

  • Fetal surveillance tests (NST, BPP) follow from abnormal 3rd-trimester screenings.