Induction of Labor

Induction of labor can be

• Medically indicated (eg, for preeclampsia or fetal compromise)

• Elective (to control when delivery occurs)

Before elective induction, gestational age must be determined. Commonly, elective induction has been avoided at 39 weeks because of lack of evidence for perinatal benefit and concern about a higher frequency of cesarean deliveries and other adverse outcomes. This practice may be changing, partly because a 2018 study showed that induction of low-risk women at 39 weeks reduced the frequency of cesarean deliveries (but not perinatal adverse outcomes) compared with expectant management (1).

Contraindications to induction include having or having had the following:

• Transfundal uterine incision (eg, for a cesarean delivery or myomectomy)

• Myomectomy involving entry into the uterine cavity

• Prior classical (vertical) cesarean incision in the thickened, muscular portion of the uterus

• Open maternal-fetal surgery (eg, myelomeningocele closure)

• Active genital herpes

• Placenta previa or vasa previa

• Abnormal fetal presentation (eg, transverse lie, umbilical cord presentation, certain types of fetopelvic disproportion)

Multiple prior uterine scars and breech presentation are relative contraindications.

If the cervix is closed, long, and firm (unfavorable), the goal is to cause the cervix to open and become effaced (favorable). Various pharmacologic or mechanical methods can be used. They include

• Prostaglandin E2 given intracervically (0.5 mg) or as an intravaginal pessary (10 mg [prostaglandins are contraindicated in women with prior cesarean delivery or uterine surgery because these drugs increase the risk of uterine rupture])

• Use of laminaria and transcervical balloon catheters, which may be useful when other methods are ineffective or contraindications exist

• 1)

Once the cervix is favorable, labor is induced.

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External fetal monitoring is routine; after amniotomy (deliberate rupture of the membranes), internal monitoring may be indicated if fetal status cannot be assessed externally. Amniotomy can be done to augment labor when the fetal head is applied to a favorable cervix and not ballotable (not floating).