The Stages of Labor – USMLE Step 2 CK

by / Wednesday, 30 June 2010 / Published in OB/GYN


It should be noted that both general and spinal anesthesia, as well as sedation may reduce uterine cavity activity if administered in the latent phase, prolonging this stage of labor.


Consider prolonged phase if it exceeds >20h in a primipara and >14hr in multiparous.  Management includes waiting for the drug to wear off.  If the patient has hypocontraction, diluted infusion of oxytocin should be administered.




Stage 1:

Latent Phase – Begins at the onset of regular contractions (If this phase arrests, therapeutic rest is the protocol)

Active Phase – Begins with the onset of cervical dilation acceleration (usually around 3-4cm).  (If this phase arrests for 2hr or more, this is an indication for C-section).

Rate of dilation in active phase: Primipara (1.2cm/hr), Multipara (1.5cm/hr)


Stage 2 :

Begins with complete cervical dilation and ends with delivery of fetus.  This may last up to 2hrs in primipara and 1hr in multipara.

Stage 3:

Begins with delivery of fetus and ends with expulsion of the placenta.  This phase may take up to 30 minutes.

  • This phase can be augmented with IV oxytocin infusion
  • Signs of stage 3 include – A gush of blood vaginally – Lengthening of the umbilical cord

Stage 4:

A 1hr-2hr period of close observation after delivery when vitals and vaginal bleeding are monitored for onset of pre-eclampsia and postpartum hemorrhage.


It should be noted that an important cause of arrest disorder is midpelvic contraction which is indicated by a prominent ischial spine(s).

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