Normal spontaneous labor

Epidemiology & Risk Factors

• Definition: Regular uterine contractions → progressive cervical change (effacement + dilation) → delivery of fetus + placenta at≥37 wks GA
• Prerequisites for labor: Uterine contractions (≥2–3/10 min), cervical ripening (↑ prostaglandins, ↓ progesterone influence), fetal descent
• Risk factors for preterm labor (pertinent contrast): infection, PPROM, prior PTL, multiple gestation, uterine anomalies, placenta previa

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Clinical Features

Signs of True Labor (vs. False Labor)

Feature	True Labor	False Labor (Braxton-Hicks)
Contractions	Regular, ↑ frequency/intensity	Irregular, no progression
Cervical change	Progressive dilation + effacement	None
Pain location	Back → abdomen	Abdomen only
Response to rest	Persists	Resolves

Stages of Labor

• Stage 1 (onset of labor → full dilation 10 cm):
  • Latent phase (0–6 cm): regular contractions begin- Nullip: normal≤20 hrs; Multip: ≤14 hrs
  • Active phase (≥6 cm → 10 cm): (ACOG 2014 redefines threshold at 6 cm)
    • Expected rate: ≥1 cm/hr dilation in active phase
• Stage 2 (full dilation → delivery of neonate):
  • Nullip:≤2 hrs (≤3 hrs w/ epidural)
  • Multip: ≤1 hr (≤2 hrs w/ epidural)
• Stage 3 (delivery of neonate → delivery of placenta):
  • Normal: ≤30 min
• Stage 4: First 1–2 hrs postpartum (recovery/monitoring)

Cardinal Movements (in order — high-yield)

1. Engagement →2. Descent → 3. Flexion → 4. Internal rotation → 5. Extension → 6. External rotation (restitution) → 7. Expulsion

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Diagnosis

True Labor Diagnosis

• Clinical: Regular contractions + documented progressive cervical change (dilation + effacement) on serial exam
• Initial test if uncertain: Cervical exam q1–2h to confirm progression

Fetal Heart Rate (FHR) Monitoring

• Category I (Normal):
  • Baseline 110–160 bpm, moderate variability, accelerations present, no late/variable decels
• Category II (Indeterminate):
  • Requires continued evaluation, possible intrauterine resuscitation (IUR)
• Category III (Abnormal — act immediately):
  • Sinusoidal pattern OR absent variability + recurrent late/variable decels
  • Mgmt: O₂, repositioning, IVF bolus, d/c oxytocin → if no improvement → emergent C/S

Key Labs

• GBS screening: At 35–37 wks (vaginal/rectal swab)
• GBS unknown at delivery → prophylaxis if: ROM≥18 hrs, fever≥38°C, GA<37 wks c
• Group and screen for all laboring pts
• CBC, T+S (type & screen)

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Differential Diagnostics

• False labor (Braxton-Hicks): No cervical change, irregular contractions, resolves w/ rest/hydration
• PPROM: Premature rupture of membranes w/o contractions; diff by ferning on slide, pooling on speculum, positive IGFBP-1/AmniSure
• Precipitous labor: Rapid labor (<3 hrs total); diff by unexpectedly fast progression,↑ risk of lacerations/PPH
• Uterine hyperstimulation (tachysystole: >5 ctx/10 min): Often oxytocin-related; FHR decels, uterine hypertonus

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Management

Stage 1 — Active Phase

• Continuous EFM (standard of care for most pts)
• Labor support: Ambulation, position changes
• Augmentation indications (inadequate progress):
  • Amniotomy (AROM): If membranes intact + head engaged
  • Oxytocin (Pitocin): Titrate to adequate contractions (Montevideo units≥200 for≥2 hrs)
• Pain management:
  • Neuraxial (epidural): Most effective; can be placed any time in active labor*(no longer contraindicated in latent phase per ACOG)*
  • IV opioids (e.g., fentanyl): Less effective, crosses placenta → neonatal respiratory depression (have naloxone ready)
  • Pudendal nerve block: For perineal repair/instrumental delivery
• GBS prophylaxis: PCN G (1st line); if PCN allergy → clindamycin or vancomycin

Stage 2 — Pushing Phase

• Passive descent recommended before active pushing (especially w/ epidural)
• Episiotomy: NOT routine; only for shoulder dystocia or imminent severe laceration
• Operative vaginal delivery (vacuum/forceps): If arrest of descent + adequate pelvis
• Arrest → C/S if: No descent ×1 hr w/ adequate pushing + epidural, or×2 hrs without

Stage 3 — Placental Delivery

• Active management (↓ PPH risk — gold standard):
  1. Oxytocin 10 units IM after delivery of anterior shoulder
  2. Controlled cord traction
  3. Uterine fundal massage after placenta delivers
• Signs of placental separation: gush of blood, cord lengthening, uterine fundus rises + becomes globular
• If placenta not delivered ×30 min → manual extraction ± evaluate for accreta

Stage 4 — Immediate Postpartum

• Monitor q15 min × 1 hr for: uterine tone, vaginal bleeding, BP, HR
• Most common cause of PPH: Uterine atony → bimanual massage + oxytocin
• Repair lacerations (classify1st–4th degree)

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Complications

Labor Dystocia (Arrest Disorders)

Disorder	Definition
Prolonged latent phase	Nullip >20 hrs; Multip >14 hrs
Active phase arrest	No dilation ×4 hrs w/ adequate ctx, or ×6 hrs w/o adequate ctx
Arrest of descent	No fetal descent ×1 hr (w/ epidural) or ×2 hrs (w/o) during Stage 2

Intrapartum

• Shoulder dystocia: Turtle sign → immediate call for help- Mgmt: McRoberts maneuver (hip hyperflexion) + suprapubic pressure (1st line); Woods screw, delivery of posterior arm, Zavanelli (last resort)
• Umbilical cord prolapse: Presenting part compresses cord → immediate C/S; elevate presenting part manually until OR
• Uterine rupture: Sudden cessation of ctx, FHR decel, maternal hemodynamic instability, loss of fetal station → emergent laparotomy

Postpartum

• PPH (>500 mL vaginal, >1000 mL C/S): 4 T’s — Tone (atony,80%), Trauma, Tissue (retained placenta), Thrombin (coagulopathy)
• Perineal lacerations:
  • 3rd degree: External anal sphincter involvement
  • 4th degree: Through rectal mucosa
• Chorioamnionitis (IAFI): Fever + uterine tenderness + maternal/fetal tachycardia → IV Ampicillin + Gentamicin (+ Clindamycin if C/S)