Induction of Labor

The goal of induction of labor is to achieve vaginal delivery through cervical dilation and uterine contractions prior to the onset of spontaneous labor. This is to be distinguished from augmentation of labor, which is the assistance of cervical dilation and or uterine contractions after labor has been diagnosed.

According to the National Center for Health Statistics, over 21.2% of live births involved induction of labor. This represents an over 100% increase from levels in 1990-1991 (9.5-10.5%). Importantly, the increase in clinically indicated induction is not increasing proportionally to the overall induction rate, suggesting that much of the rise in induction rates are due to elective inductions. An elective induction is typically considered as the initiation of labor without an obstetrical or medical reason.

Why Induction of Labor Is Done

In general, induction of labor is indicated when the risks of continuing the pregnancy outweigh the risks associated with delivery.

Labor may sometimes be induced for logistical reasons (e.g. a patient with a history of rapid labor, or who lives far from the hospital) or for psychosocial reasons as long as fetal pulmonary maturity is documented or the pregnancy is documented to be 39 weeks' gestation or greater. Macrosomia, pending macrosomia, and history of shoulder dystocia are not credible indications for induction of labor.

How Induction of Labor Is Done

If the cervical exam already shows dilation and shortening, induction is often initiated with oxytocin, an intravenous medication to stimulate contractions.

If the cervix does not show such changes, preinduction cervical ripening is often necessary. Preinduction ripening aims to soften and dilate the cervix prior to the onset of contractions. This can be achieved pharmacologically (with prostaglandin medications, such as misoprostol or dinoprostone, administered vaginally) mechanically (with a transcervical Foley catheter balloon or laminaria).

Transcervical Foley catheter balloon ripening is becoming a more popular form of induction of labor, as it shows similar clinical effectiveness to the prostaglandin agents. Some natural methods of induction include membrane stripping during a vaginal exam, amniotomy (rupture of the fetal membranes), nipple stimulation, and intercourse.

Benefits

The benefit of induction of labor is that a trial for vaginal delivery is possible, when delivery is indicated. Without an attempt at induction, cesarean delivery is the only alternative if delivery must be performed prior to the onset of labor.

Risks

Complications

Induction of labor is associated with a 50-100% increase in risk of cesarean delivery when compared to patients going into spontaneous labor. The risk is primarily in patients who have not previously given birth and those with an unfavorable cervical exam.

Complications of prematurity are another concern with induction. This is why it is so important to document lung maturity or ensure the patient is 39 weeks gestation or more before starting an induction.

Side Effects

Medical induction of labor is often associated with hospitalization. Often, particularly when prostaglandins or oxytocin is used, continuous fetal heart rate monitoring is necessary.

Experts on Induction of Labor

Doctors and specialists

Christian M. Pettker, MD

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References

External Links

American College of Obstetricians and Gynecologists