Labor induction and augmentation

Labor induction

As the end of pregnancy nears, the cervix normally becomes soft (ripe) and begins to open (dilate), preparing for labor and delivery. When labor does not naturally start on its own and vaginal delivery needs to happen soon, labor may be started artificially (induced). While this is a fairly common practice, childbirth educators encourage women to learn about labor induction as well as medication for stimulating a stalled labor (augmentation) so they can help decide what is right for them.

When labor does not happen as expected or as necessary, inducing labor is preferred over delivering by cesarean section. If labor induction isn't successful, another attempt may be possible. In some cases, a cesarean delivery is best for the mother and baby, depending on their conditions.

There are several ways to induce labor contractions.

• If your cervix is not ripe, medication is first used to soften it.
• If your cervix is ripe but active labor has not started, labor can be induced by rupturing the amniotic sac (amniotomy).
• If labor does not progress after an amniotomy, medication such as oxytocin (Pitocin) can be used to stimulate contractions.

Your labor may be induced for one of the following reasons:

• Your pregnancy has gone 1 to 2 weeks past the estimated due date.
• You have a condition (such as high blood pressure, placenta abruptio, infection, lung disease, preeclampsia, or diabetes) that may threaten your health or the health of your baby if the pregnancy continues.¹
• Your water (amniotic sac) has broken, but active labor contractions have not started.
• Your baby has a condition that needs treatment, and the risks of vaginal delivery are low. Induction and vaginal delivery are not attempted if the baby may be harmed or is in immediate danger. In such cases, a cesarean delivery (C-section) is usually performed.

Medication to ripen the cervix

• Dinoprostone (such as Cervidil or Prepidil Gel) can be inserted as a suppository into your vagina (intravaginally). It can also be given as a gel that is gently squirted into the opening of the cervix (intracervically). Once the cervix is ripe, labor may start on its own.
• Misoprostol (Cytotec) is a pill taken by mouth or placed in the vagina (using a smaller dose). It is a medication currently approved for treating ulcers; using it for cervical ripening is a widely accepted but unlabeled use of this medication.²
• Oxytocin (Pitocin) can be given through a vein (intravenously) in small amounts to ripen the cervix. However, it usually is given after the cervix softens to cause the uterus to contract. Labor that is induced by oxytocin usually starts off harder and progresses faster than labor that starts on its own, especially in first-time mothers. If oxytocin does not induce labor or if the baby's heart rate indicates distress, a cesarean delivery (C-section) may be necessary.

The cervix is considered ripe and ready for active labor when it is soft, well-dilated, and effaced and when the cervix and baby are positioned low in the pelvis (as measured by a Bishop score greater than 5 out of 10). If the cervix is not ripe enough and the Bishop score is low, medications may be continued until the Bishop score reaches 8 or higher.

Artificial rupture of the membranes to induce labor

To start or speed up labor, your health professional may rupture your amniotic sac (rupture of the membranes). This should only be done after your cervix has started to open (dilate) and the baby's head is firmly descended (engaged) in your pelvis. If the membranes are ruptured too early, there is a risk of the umbilical cord slipping down around or below the baby's head (cord prolapse). If the cord gets squeezed between the baby's head and the pelvis bones, the blood supply to the baby may be decreased or stopped.

To rupture your amniotic sac (amniotomy), your health professional inserts a sterile plastic device into your vagina; this may look like a long crochet hook or may be a smaller hook attached to the finger of a sterile glove. The hook is used to pull gently on the amniotic sac until the sac breaks. This procedure is usually not painful. A large gush of fluid usually follows the rupture of the amniotic sac. The uterus continues to produce amniotic fluid until the baby's birth, so you may continue to feel some leaking, especially right after a hard contraction.

Augmentation

If active labor has started on its own but contractions have slowed down or completely stopped, steps need to be taken to help labor progress (augmentation). Augmentation will be done when:

• Active labor has started, but your contractions are weak or irregular or have stopped entirely.
• You have gone into active labor, but the amniotic sac has not ruptured on its own. In this case, your doctor or nurse midwife may rupture the amniotic sac (amniotomy) to augment labor. If labor still does not progress, oxytocin (Pitocin) may be given to make the uterus contract.
• Active labor has started and the amniotic sac has ruptured on its own, but labor still is not progressing. Oxytocin (Pitocin) may be given to make the uterus contract.

For some women, laboring in a warm tub or whirlpool (under medical care) helps with a slow labor. This can make augmentation unnecessary.³

If labor fails to progress in spite of an amniotomy, oxytocin, or both, delivery by cesarean section may be considered.

Citations

1. American College of Obstetricians and Gynecologists (1999). Induction of labor. ACOG Practice Bulletin No. 10. Obstetrics and Gynecology, 94(5, Part 1): 1–10.

2. Harman J, Andrew K (1999). Current trends in cervical ripening and labor induction. American Family Physician, 60(2): 477–484.

3. Cluett ER, et al. (2004). Randomised controlled trial of labouring in water compared with standard of augmentation for management of dystocia in first stage of labour. BMJ, 328(7435): 314–320.