Labour Induction and Augmentation
As the end of pregnancy nears, the cervix normally becomes soft (ripe) and begins to open (dilate) and thin (efface), preparing for labour and delivery. When labour does not naturally start on its own and vaginal delivery needs to happen soon, labour may be started artificially (induced).
Even though inducing labour is a fairly common practice, childbirth educators encourage women to learn about it and about the medicine for stimulating a stalled labour (augmentation) so that the women can help decide what is right for them.
When labour is induced for medical reasons, it is usually because it's safer for you to have the baby now rather than risk further problems from staying pregnant.
Your labour 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, abruptio placenta, infection, lung disease, pre-eclampsia, or diabetes) that may threaten your health or the health of your baby if the pregnancy continues.footnote 1, footnote 2
- Your water (amniotic sac) has broken but active labour 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 caesarean delivery (C-section) is usually done.
Some women ask to have their labour induced when there isn't a medical reason for it (elective induction). And sometimes doctors will induce labour for non-medical reasons, such as if you live far away from the hospital and may not make it to the hospital if you go into labour. In these situations, your doctor will wait until you are at least 39 weeks, because this is safest for your baby.
When labour does not happen as expected or as needed, inducing labour is preferred over delivering by caesarean section. If labour induction isn't successful, another attempt may be possible. In some cases, a caesarean delivery is best for the mother and baby, depending on their conditions.
Ways to induce labour
There are several ways to induce labour contractions.
- Medicine may be used to soften the cervix and help it thin (efface).
- Medicine may be used to cause the uterus to contract.
- A balloon catheter (such as a Foley catheter) may be used to help the cervix open.
- If your cervix is soft and slightly open, sweeping the membranes or rupturing the amniotic sac (amniotomy) may start or increase contractions.
Medicine to ripen the cervix and induce labour
- Misoprostol is a pill taken by mouth or placed in the vagina (using a smaller dose). It is a medicine currently approved for treating ulcers. Using it for cervical ripening is a widely accepted but unlabeled use of this medicine.
- Oxytocin can be given through a vein (intravenously) in small amounts to ripen the cervix. But it usually is given after the cervix softens, to cause the uterus to contract. Labour that is induced by oxytocin usually starts off harder and progresses faster than labour that starts on its own, especially in first-time mothers. If oxytocin does not induce labour or if the baby's heart rate indicates distress, a caesarean delivery (C-section) may be needed.
- 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). When the cervix is ripe, labour may start on its own.
The cervix is thought to be ripe and ready for active labour when it is soft, well dilated, and effaced, and when the cervix and baby are positioned low in the pelvis. If the cervix is not ripe enough, medicines may be continued until it is.
Balloon catheter to help induce labour
A balloon catheter, such as a Foley catheter, is a narrow tube with a small balloon on the end. The doctor inserts it into the cervix and inflates the balloon. This helps the cervix open (dilate). The catheter is left in place until the cervix has opened enough for the balloon to fall out (about 3 cm).
Sweeping of the membranes to help induce labour
Sweeping, or stripping, of the amniotic membranes is a simple first step used to try to start labour. Sweeping of the membranes separates the amniotic membrane from the uterus enough so that the uterus starts making prostaglandins. This type of chemical helps trigger contractions and labour. After the cervix is open a little, this step can easily be done in your doctor's or midwife's office.
Sweeping the membranes works in 1 out of 8 women. This means that it starts labour without needing to use oxytocin or artificially rupture the membranes.footnote 3 To sweep the membranes, your doctor or midwife reaches a gloved finger through the cervix. He or she then "sweeps" the finger around the inside edge of the opening.
Sweeping the membranes is low-risk. It does not raise your risk of infection. You may start to feel uncomfortable afterward, with irregular contractions and some bleeding.footnote 3
Artificial rupture of the membranes to induce labour
To help start or speed up labour, your doctor 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 pelvic bones, the blood supply to the baby may be reduced or stopped.
To rupture your amniotic sac (amniotomy), your doctor inserts a sterile plastic device into your vagina. This device 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.
If active labour has started on its own but contractions have slowed down or completely stopped, steps need to be taken to help labour progress (augmentation). Augmentation will be done when:
- Active labour has started, but your contractions are weak or irregular or have stopped entirely.
- You have gone into active labour, 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 labour. If labour still does not progress, oxytocin may be given to make the uterus contract.
- Active labour has started and the amniotic sac has ruptured on its own, but labour still is not progressing. Oxytocin may be given to make the uterus contract.
If labour fails to progress in spite of membrane sweeping, an amniotomy, oxytocin, or a combination of these measures, delivery by caesarean section may be considered.
- Society of Obstetricians and Gynaecologists (2013). Induction of labour at term. SOGC Clinical Practice Guideline No. 296. Journal of Obstetrics and Gynecology Canada, 35(9): 840–857. Available online: http://www.jogc.com/abstracts/201309_SOGCClinicalPracticeGuidelines_1.pdf.
- American College of Obstetricians and Gynecologists (2009, reaffirmed 2013). Induction of labor. ACOG Practice Bulletin No. 107. Obstetrics and Gynecology, 114(5, Part 1): 386–397.
- Boulvain M, et al. (2005). Membrane sweeping for induction of labour. Cochrane Database of Systematic Reviews (1).
Primary Medical Reviewer Kathleen Romito, MD - Family Medicine
Thomas M. Bailey, MD - Family Medicine
Specialist Medical Reviewer Kirtly Jones, MD - Obstetrics and Gynecology
Current as ofMay 22, 2015
Current as of: May 22, 2015
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