The definition of labor is the presence of uterine contractions of sufficient intensity to bring effacement and dilation of the cervix. Women in labor enter the active phase when cervical dilation is between 3cm and 4cm. The active phase of labor includes an increased rate of cervical dilation and descent of the presenting fetal part. A practical classification is to categorize labor abnormalities as slower-than-normal or complete cessation of progress disorders.
Augmentation refers to stimulation of uterine contractions. Augmentation should be considered if the frequency of contractions is less than 3 contractions per 10 minutes.
In a nulliparous woman, the diagnosis of a prolonged second stage should be considered when second stage exceeds 3 hours if regional anesthesia has been administered or 2 hours if no regional anesthesia is used. In multiparous women, the diagnosis can be made when the second stage exceeds 2 hours with regional anesthesia or 1 hour without.
The goal of oxytocin is to effect uterine activity sufficient to produce cervical change and fetal descent. Typically, a goal of a maximum of 5 contractions in a 10 minute period with resultant cervical dilation is considered adequate.