Defining arrest in the first and second stages of labor.

Normal labor is identified as regular uterine contractions in addition to dilation and effacement of the cervix. It is necessary to define normal labor in order to delineate when a woman's labor pattern diverges from that observed in most women. Labor irregularities are subdivided into protraction disorders and arrest disorders. Identifying abnormal labor patterns and initiating appropriate interventions is essential because prolonged labor is associated with an increase in perinatal morbidity. The aim of this review was to delineate both normal labor progress and also discuss the current evidence-based diagnosis and treatment of protraction and arrest disorders. Many subtleties go into defining the boundaries of the first and second stages of labor. Historically, the Friedman curve established normal limits; but currently Zhang has advanced these definitions by accounting for current demographical characteristics and practice environments. The most significant variables for defining normal progress of labor are parity and regional anesthesia status. The most common causes of labor abnormalities are uterine inactivity, obesity, cephalopelvic disproportion and fetal malposition. Risks of extending the first and/or second stage of labor include postpartum hemorrhage, intraamniotic infection and potentially an increase in neonatal adverse outcomes. The management of labor disorders consists of oxytocin administration, amniotomy, intrauterine pressure catheter use and shared decision-making regarding proceeding with expectant management, operative vaginal delivery or cesarean delivery after weighing the risks and benefits of each option. The decision to extend the duration of labor is personalized for each mother-baby dyad and should be agreed upon depending on individual maternal and fetal circumstances.