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Labor and Delivery

Active Management of Labor

A system of labor management for nulliparous women, termed active management of labor, has been developed and practiced in Ireland over the last three decades. The original motivation for implementing active management of labor.

Women are instructed during pregnancy as to signs and symptoms of labor and are encouraged to present early in labor. The diagnosis of labor is made initially by the woman herself and is confirmed by a senior health care provider. Confirmation depends on painful uterine contractions and one of the following: passage of a mucus plug, complete effacement, or spontaneous rapture of membranes. Progress in labor during the first stage is measured in terms of cervical dilatation only. Progress in the second stage is a function of time and is abnormal if longer than 2 hours. Membranes are ruptured, if intact, at 1 hour after admission. A vaginal examination is performed hourly, and oxytocin infusion is begun if there is not a change of at least 1 cm in dilatation since the last examination. The method consists of diluting 10 units of synthetic oxytocin into a liter of dextrose solution. The resulting solution (10 mU/mL) is infused by counting drops per minute. Approximately 15-20 drops are equivalent to 1 mL.

Labor Stimulation

The stimulation of uterine contractions may be characterized as labor induction or labor augmentation. Induction of labor implies stimulation of uterine contractions in their prior absence, with or without ruptured fetal membranes. Labor induction may be elective or indicated. Elective induction of labor is defined as the initiation of labor.

Timing of amniotomy is very important for maximizing the number of vaginal deliveries and for reducing the number of operative deliveries during labor induction. Once amniotomy is performed, the patient is committed to delivery. Induction of labor in a woman with a favorable cervix by amniotomy or a combination of amniotomy and oxytocin.

The state of the cervix is related to the success of labor induction. A cervical scoring system designed by Bishop has been used by many to predict inducibility, with a score of 4 or less considered unfavorable (Table 15). In a patient with an unfavorable cervix, many advocate the use of cervical-ripening agents, including extraovular catheters, osmotic dilators, prostaglandins (E_l, E2, F2ct), and locally applied hormones such as relaxin or estrogens. Prostaglandins have been shown to enhance cervical effacement and dilatation; increase the chance of successful induction; and reduce the time, dose, and need for oxytocin (Table 16).

Prostaglandin

Prostaglandin E₂ (PGE2) and PGF22a are as effective as oxytocin for the induction of labor at term and even more effective in early and midpregnancy, when the uterus is more refractory to oxytocin. Prostaglandin E₂ can be given intravenously, orally, intravaginally as suppositories or a gel, and intraamniotically. Side effects are few and include fever, vomiting, and diarrhea. There is a risk of uterine rupture when prostaglandins are used after 28 weeks of gestation.

Prostaglandin is the preferred agent for preinduction cervical ripening. Whereas some analyses claim that prostaglandin given for cervical ripening reduces the rates of failed induction, cesarean birth, and instrumental vaginal delivery, a randomized double-blind study and meta-analysis of 18 studies involving 1,811 patients found that a single dose of intracervical PGE₂ for cervical ripening had little effect on labor induction.

Intrapartum Fetal Heart Rate Monitoring

The goal of intrapartum FHR monitoring is to detect signs of fetal jeopardy in time to intervene before irreversible fetal damage occurs. Despite the liberal use of continuous electronic fetal monitoring and operative delivery, there has been no consistent decrease in the frequency of cerebral palsy in the past two decades.