II. Definition: Fetal Station
- Zero Station Notation (presenting part level)
- Presenting part in relation to ischial spines
- Reported in centimeters from ischial spines
- Negative numbers are behind the ischial spines
- Engagement
- Refers to presenting part meeting pelvic floor
- Occurs at 0 station
III. Step 1: Fetal Descent
- Fetal head position on abdominal palpation
- Head fixed: 3/5 palpable abdominally
- Head engaged: 2/5 palpable abdominally
- Fetal Heart Tones change position (towards Pelvis)
IV. Step 2: Fetal neck flexion
- Partial flexion prior to labor (natural fetal tone)
- Flexion of Cervical Spine (chin to chest) with descent
- Occiput Anterior
- Presenting diameter changes from occipitofrontal
- Transforms into smaller suboccipitobregmatic
- Posterior Fontanelle to sub-occiput
- Occiput Posterior
- Incomplete flexion
- Larger presenting diameter
- Prolonged labor
- Occiput Anterior
V. Step 3: Internal Rotation
-
Occiput Anterior
- Occiput initially transverse or oblique
- Occiput rotates anteriorly towards Symphysis Pubis
- Occurs as presenting part reaches pelvic floor
- Engagement (ischial spines: Zero station)
-
Occiput Posterior
- Possibility 1
- Head rotates posteriorly
- Occiput turns to hollow of Sacrum
- Possibility 2 (75% of cases)
- Occiput Posterior converts to Occiput Anterior
- Fetus Rotates 90 degrees
- Possibility 1
VI. Step 4: Extension
-
Occiput Anterior
- Head extends to meet the vaginal outlet
- Oriented upward and forward
- Crowning occurs (+5 Station)
-
Occiput Posterior
- Combination of flexion and extension
VII. Step 5: External Rotation (Head delivered)
- Delivered head returns to position at engagement
- Head aligns with back and Shoulders