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Medical Induction of Labor

In the United States, medical induction of labor is common. More than 50% of women report that their physicans offer labor induction.

Reasons for Medical Induction

There are many reasons labor may be induced. These will be divided into medical reasons and social reasons.

Medical Reasons

  • Non-reassuring fetal testing
  • Infant size - though it has been shown that cesareans are more likely to occur with induction than with large size
  • Post dates - defined by ACOG as 42 weeks; many practices begin induction at 41 weeks
  • Gestational diabetes - research indicates great problems with placentas at the end of pregnancy in diabetic women
  • Pre-eclampsia - The cure for this potentially serious condition is delivery

Social Inductions

Social inductions are common in some hospitals, and discouraged in others. Common reasons include:
  • Convenience of having it scheduled
  • Long drive to the hospital
  • Preference for a particular date - particularly if it fits work or travel schedules
  • Desire to deliver when a particular practitioner is on call

Risks of Medical Induction

Two primary risks of induction are cesarean and preterm delivery. Other complications are less common.

Cesarean Delivery

Approximately 50% of women who are induced end up being delivered by cesarean. This is often because the induction was not successful in accomplishing a vaginal delivery.

Fetal distress from pitocin is another reason that the induction may end in cesarean delivery. Some practices have a more lenient approach to medical inductions. If it is not successful, they may discuss with the woman the possibility of turning everything off, letting her go home, and trying again in two or three days. This gives the woman a greater chance of delivering vaginally.

Preterm Delivery

Many inductions in the past have resulted in babies born before their lungs were mature. This can occur because of a miscalculation in the due date or in the practice of inducing before the anticipated due date.

Current guidelines advise against induction before 39 weeks of pregnancy.

Methods of Medical Induction

Cervical Ripening Agents

Cervical ripening agents are frequently used as the first step of a medical induction. If the induction with pitocin is unsuccessful, a cesarean is needed. Therefore cervical ripening agents are used on women who have a Bishop score of six or less.


Sponge like dilators can be placed into the cervix, which will absorb the fluid from the vagina and cause cervical dilation. These products include:
  • Laminaria, a naturally occurring product
  • Lamicel, a similar, synthetic product
  • Foley catheter (the catheter from a foley bladder catheter can be place in the cervix and the balloon inflated.
The mother can go home after the Laminaria or Lamicel are placed and return later to evaluate the changes in the cervix. Usually she will remain in the hospital if the foley is placed.

Risks of dilators

  • Infection
  • Bleeding
  • Rupture of membranes
  • disruption of the placenta



Prostaglandin preparations are also used to soften the cervix prior to as part of a medical induction. Prepidil (dinoprostone gel) is a gel that is applied to the cervix through a catheter if the Bishop score is less than 4. The mother needs to remain in bed for half an hour to insure the gel is retained in the cervical tissue. Because of the risk of fetal distress, it is necessary to monitor the infant’s heart rate and the number of uterine contractions before and after application of Prepidil. The procedure may be repeated in six hours, with up to three applications in 24 hours. Pitocin should not be started for more than six hours due to the risk of uterine hyper-stimulation. The application of the gel will not be repeated if the Bishop score is eight or more, if labor has started, or there is deterioration in the fetal heart rate.


Cervidil (dinoprosterone insert) is another prostaglandin product that can be used with a cervix with a Bishop score of less than 4. The pessary is a small device that is placed in the posterior fornix of the cervix with lubricant. The medication will be released as the pessary absorbs moisture and enlarges. The mother needs to lie in bed for two hours after the device is placed and monitored during the time it is left inside. It will be removed in twelve hours, or if labor starts, or there is fetal distress. Monitoring is required due to the risk of fetal distress or uterine hyper-stimulation.


Cytotec is a synthetic prostaglandin agent often used for cervical ripening several hours before a pitocin induction. There is a controversy surrounding Cytotec. Advocates of this medication as a cervical agent point out that research has demonstrated a lower rate of pitocin use and a decrease in the number of cesareans due to the effectiveness of the medication to soften the cervix and induce contractions.

Critics of Cytotec state that its effectiveness also causes a greater number of hyper-stimulated contractions, which have led to increased incidence of uterine rupture in women attempting Vaginal Birth after a Cesarean. This has contributed to the current practice of discouraging VBACs.

In addition, Cytotec is not labeled by the FDA or by the manufacturer for use as a cervical agent for medical inductions. It is approved for people who have developed gastrointestinal ulcers after taking aspirin. Nonetheless, it remains a popular option as many physicians appreciate its effectiveness of preparing a cervix prior to pitocin administration.

A tablet of Cytotec (or a part of a tablet) is placed in the vagina near the cervix. The mother needs to remain lying down for 30 minutes after application to keep it in place. She remains in bed and is monitored for 3 hours after it is inserted. It may be repeated every four to six hours if the cervix remains unfavorable. Pitocin should not be started until three hours after the last administration due to the danger of hyper-stimulation.

Disrupt Membranes for Labor Induction

Other methods used to induce labor include disruption of the amniotic membranes.

Stripping Membranes

Stripping the membranes is a procedure where the physician or midwife scrapes the membrane with his or her finger through the partially opened cervix.

A risk of this procedure is that the membranes may rupture before the cervix is softened leading to a likely cesarean. It also carries the risk of infection, hemorrhage, and pain.

Advantage of the procedure is that first-time mothers who were induced with stripping membranes and pitocin had a lower rate of cesarean (17%) compared to first time mothers with pitocin alone. (42%) In many cases, patients are unaware that the physician stripped their membranes during a pelvic exam, which is an unethical situation at best.


Amniotomy is a common obstetrical procedure which causes the amniotic sac to rupture. It can be used to induce labor, with or without pitocin. It can also be used to augment labor that is not progressing as fast as desired.

An amniotomy hook is inserted through the cervical os and the membranes ruptured by a physician or midwife. Once the bag of membranes have ruptured, the mother is put on a schedule to make sure she delivers in a specified time limit or a cesarean is done to prevent infection.

Risks of Amniotomy

Risks of amniotomy include:
  • Umbilical cord prolapse
  • Infection
  • Fetal distress
  • hemorrhage from a low-lying placenta

Pitocin Induction

The majority of medical inductions use pitocin. Pitocin inductions use the IV medication pitocin, which is a synthetic substitute for a woman's naturally occuring hormone, oxytocin. Oxytocin is the substance which causes uterine contractions. Pitocin works by making the uterus contract.

Pitocin induced labors are more painful for the majority of women than labor that starts spontaneously. The intensity of contractions is stronger. Most women who use pitocin do opt for pain medication in order to deal with the more intense contractions.

What to Expect with a Medical Induction

There is no one formula for labor induction that will dictate what will happen with any particular woman's labor. Factors that influence the course of the induction include:
  • If the cervix is already soft or dilated
  • How many children she has born before
  • History of cesarean
  • Preference of physician and hospital
  • Availability of labor rooms
  • Rapidity with which labor begins
While it is not possible to predict how any one labor will be induced, it is possible to describe common scenarios. Generally, the order of induction is:
  • Stripping membranes at last office appointment prior to induction
  • One or two doses of cervical ripeneing agent (may or may not be admitted to hospital)
  • Pitocin
  • Amniotomy
  • Epidural
Often the pitocin is turned off after the amniotomy - if the uterus begins contracting sufficiently on its own. It may be started again if the contractions become weaker.

Prior to scheduling an induction, it is wise to clafify the reason for the induction and the induction plan that is usually used by your practitioner.

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By Karen Newell Copyright 2003 - 2012 Better Childbirth Outcomes - All Rights Reserved
Camp Hill, Pennsylvania, USA