Lecture Notes on Labor and Delivery

Introduction to Labor

• Parturition: Hard work of delivering a baby.
• Process: Starts with uterine contractions -> cervical changes -> ends with placenta delivery.
• Timing: Begins between 37-42 weeks gestation (full term).

Signs of Labor Beginning

• Bloody Show: Plug of mucus and blood falls out of cervix.
• Water Breaking: Amniotic sac rupture.
• True Labor Contractions: Distinct from Braxton Hicks contractions.

Labor Contractions

• Progression: Frequency, duration, intensity increase.
• Cervical Changes: Effacement (thinning) and dilation (opening).
• First-time Pregnancy Duration: Typically 12-18 hours; shorter for subsequent pregnancies.

Stages of Labor

First Stage

• Phases:
  • Latent Phase: Up to 20 hours; cervix dilates to 6 cm; contractions become regular.
  • Active Phase: Cervix dilates from 6 to 10 cm; intense contractions.
• Amniotic Sac Rupture: Often occurs by this point.

Second Stage (Pushing Stage)

• Key Factors (3 P's):
  • Power: Uterine contractions.
  • Passenger: Fetus.
  • Passage: Bony pelvis.
• Fetal Considerations:
  • Size: Head size critical.
  • Attitude: Position of flexion important.
  • Lie: Longitudinal is ideal.
  • Presentation: Cephalic (head-first) optimal.

Cardinal Movements

• Descent: Downward movement (fetal station -5 to 0).
• Flexion: Chin-to-chest as head meets resistance.
• Internal Rotation: Align shoulders with pelvic inlet.
• Extension: Head changes from flexion to extension.
• Restitution: Head rotates externally.
• Expulsion: Delivery of shoulders and body.

Third Stage

• Placenta Delivery: Uterus contracts, placenta separates and is removed.

Fourth Stage (Post-Delivery)

• Physiologic Changes: Blood loss adaptation, uterine involution.

Recap

• Labor Stages:
  • First stage: True contractions to full dilation.
  • Second stage: Pushing and birth.
  • Third stage: Placenta delivery.