Stages and the contemporary curve
| Stage | From | To | Notes |
|---|---|---|---|
| First, latent | Onset of regular contractions | 6 cm | Slow and variable; can last many hours. A prolonged latent phase is not an indication for caesarean. |
| First, active | 6 cm | Full dilatation | Faster, roughly 0.5 to 1 cm per hour or more; slower than the old 1.2 cm per hour rule is still normal. |
| Second | Full dilatation | Birth | Up to 3 hours in a first labour (4 with an epidural), 2 in a subsequent one (3 with an epidural), as long as progress continues. |
| Third | Birth | Delivery of the placenta | Active management (oxytocin at delivery, controlled cord traction after signs of separation) shortens it and reduces haemorrhage. |
ACOG/SMFM Obstetric Care Consensus (2014), based on the Zhang labour curves.
The cervical examination
- Consent every time, chaperone offered, explain what you will do and stop when asked.
- Dilatation in centimetres (0 to 10), effacement in percent (or length in centimetres), station relative to the ischial spines (minus 3 to plus 3), consistency, position of the cervix, and the presenting part: what it is, its position (occiput anterior, posterior, transverse by the sutures and fontanelles), caput and moulding.
- Membranes intact or ruptured; liquor colour.
- Fewer examinations are better: every 4 hours in active labour is the usual rhythm, more often when a decision depends on it.
Bishop score and cervical examination in the procedures pages
The mechanism of labour (occiput anterior)
- 1
Engagement
The widest diameter of the head passes the pelvic inlet, usually transverse. In a first pregnancy this often happens before labour.
- 2
Descent
Driven by contractions and, in the second stage, by pushing.
- 3
Flexion
The chin tucks, presenting the smallest diameter (suboccipitobregmatic, 9.5 cm).
- 4
Internal rotation
The occiput turns from transverse to anterior at the level of the ischial spines, following the shape of the pelvic floor.
- 5
Extension
The head delivers by extending under the symphysis: occiput, then brow, face and chin.
- 6
Restitution and external rotation
The head turns back to line up with the shoulders, which then rotate into the anteroposterior diameter.
- 7
Expulsion
The anterior shoulder under the symphysis, then the posterior, then the body.
Care in labour
- Intermittent auscultation for low-risk labour (every 15 to 30 minutes in the first stage, every 5 minutes in the second, for 60 seconds after a contraction); continuous electronic monitoring when there are risk factors or a concern.
- Analgesia options: mobility, water, TENS, nitrous oxide, opioids, epidural. An epidural does not raise the caesarean rate; it lengthens the second stage a little.
- Oral intake of clear fluids; avoid routine intravenous fluids; encourage upright and mobile positions.
- Support: one-to-one care in labour is one of the best-evidenced interventions in obstetrics.
Watch it done
Engagement, descent, flexion, internal rotation, extension, restitution and external rotation, animated on the pelvis.
Lie, presentation and position on a model, the vocabulary the board and the partogram use.
On the modelCervixIsthmus and lower segmentBony pelvisPelvic floor