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.