Abnormal Labor

Normal labor is defined as regular uterine contractions resulting in progressive cervical effacement and dilation. Abnormal labor refers to labor patterns deviating from delineated normal standards. A clear understanding of normal labor progression is essential to recognize dysfunctional labor.

Labor consists of 3 stages. The first stage begins with contractions causing progressive cervical change and concludes with full cervical dilation. The first stage is further divided into latent and active phases. The second stage of labor starts with complete cervical dilation and ends with delivery of the fetus. The third stage begins with delivery of the fetus and ends with placental delivery. Abnormal labor occurs across all stages and is described as a prolonged, protracted, or arrested progression of labor.

The stages and phases of labor have specific time intervals used in labor evaluation and interpretation. Ideally, patients are evaluated with or without pelvic examinations every 2 hours to assess labor progress.

1. First Stage: 0 to 10 cm dilation

   1. Latent phase: 0 to 5 cm dilation

   2. Active phase: 6 cm dilation to complete cervical dilation

2. Second Stage: uterine contractions along with maternal expulsive efforts leading to the descent of the presenting fetal part and delivery of the fetus

3. Third Stage: time between delivery of the fetus and placental delivery

The following parameters apply to full-term singleton pregnancies and represent the time 95% of patients will complete a given stage or phase of labor. These parameters should be met when classifying labor as abnormal:

First Stage Prolongation, Protraction, and Arrest

1. Latent Phase Prolongation

   1. In nulliparous patients: latent phase duration of more than 20 hours

   2. In multiparous patients: latent phase duration of more than 4 hours

   3. Due to its variable and slow progression, latent phase prolongation alone is not an indication for cesarean delivery.

1. Active Phase Protraction and Arrest (once 6 cm cervical dilation is achieved)

   1. No cervical dilation after 4 hours of adequate contractions, with ruptured membranes

   2. No cervical dilation after 6 hours of inadequate contractions, with ruptured membranes, and despite oxytocin administration

Second Stage Protraction and Arrest

1. For nulliparous patients: second stage duration of more than 3 hours without an epidural or 4 hours with an epidural

2. For multiparous patients: second stage duration of more than 2 hours without an epidural or 3 hours with an epidural

3. Longer durations may be appropriate with reassuring maternal and fetal statuses and continued descent of the fetal presenting part.

Third Stage Abnormality

1. Placental retention duration of more than 30 minutes following fetal delivery