Childbirth: Inducing labour

A vaginal delivery requires that the woman’s cervix be dilated to 10 cm. This takes time and patience, especially if it’s the mother’s first child, because the body isn’t accustomed to giving birth.

Sometimes, nature needs a little nudge and labour has to be induced. Artificial labour induction starts the contractions that help open the cervix.

What’s the purpose of inducing labour?

Inducing labour shouldn’t be confused with stimulating labour. When labour is stimulated, that means contractions have already begun. The purpose of stimulation is to increase the intensity, duration, and frequency of contractions by administering an intravenous drug called oxytocin.

Your doctor may recommend artificial labour induction for several reasons. In most cases, it’s recommended because the pregnancy has surpassed its normal term. According to the Society of Obstetricians and Gynaecologists of Canada, pregnant women should be offered the option of having labour induced between weeks 41 and 42 of their pregnancy, as this would reduce the risk of a stillbirth or infant death in the days following delivery.

This procedure is also necessary when a woman’s water breaks before contractions begin naturally. When the baby is no longer protected by this fluid, the risk of infection increases for both mother and baby.

How is labour induced to open the cervix?

There are several ways to induce labour to open the cervix. If your doctor decides that labour should be induced, they’ll explain which method they feel is best for your situation. The choice of method depends on certain factors.

It’s important for you to consent to the methods used to induce your labour. This means you need to understand all potential advantages, disadvantages, and contraindications of using these methods. If you have any questions, discuss them with your doctor or midwife.

Sweeping the membranes

While in the womb, your baby is immersed in amniotic fluid, which protects them. A large bag made up of two membranes holds the fluid inside the uterus. This is known as the amniotic sac.

Toward the end of your pregnancy, your doctor may suggest stimulating the ripening of your cervix by sweeping the membranes from the uterine lining. This simple procedure can be performed in the doctor’s office. When examining your cervix, the doctor will place their fingers near the opening of the cervix and gently separate the membrane from the uterus. This technique triggers the local release of hormones known as prostaglandins, which gradually help to start contractions.

Some doctors suggest repeating the procedure every week as of the 38th week of pregnancy. Membrane sweeping can also be done every day as of the 41st week.

For many women, labour starts within 48 hours of membrane sweeping. In fact, some studies suggest that this method of labour induction helps reduce the risk of a pregnancy extending beyond 41 weeks. In addition, women who undergo this procedure appear less likely to require other labour induction methods.

However, some women feel pain during this procedure or discomfort afterward. This is because membrane sweeping can irritate the uterus and lead to mild uterine contractions. Membrane sweeping can also cause ineffective contractions that don’t induce labour. Moreover, using this method may cause slight bleeding for 24 hours since the cervix is full of small blood vessels that can rupture. However, any bleeding that occurs should be lighter than menstrual bleeding. If heavier bleeding occurs, it’s best to contact your birth location so the situation can be assessed.

Rupture of the membranes

A common method of inducing labour is to rupture the membranes and wait a few hours to see if contractions start on their own. This is known as artificial rupture of the membranes. The doctor will first perform a vaginal examination to ensure the baby is engaged and pressing on the cervix. The cervix must be at least 2 cm dilated before the doctor can rupture the membranes. To do this, they locate the bag of waters surrounding the baby and break it using a small plastic hook. You may feel some discomfort during the exam, but this method is painless for you and your baby.

Prostaglandin gel vs. balloon catheter

Another common way to induce labour involves inserting prostaglandin gel or a piece of prostaglandin-soaked cloth into the cervix. The prostaglandins in the gel or cloth will cause contractions that may help with dilation and the thinning of the cervix. This technique may reduce the duration of the induction and the amount of oxytocin needed to induce labour.

Sometimes a balloon is used to promote cervical ripening and dilation. This is done by inserting a catheter with a balloon at the end of it into the vagina. Once the balloon is inserted into the cervix, it is inflated with a saline solution. The balloon applies pressure to the cervix to help it dilate. The insertion of the balloon can cause discomfort; it may even hurt because of the pressure exerted on the cervix and the contractions caused by the prostaglandins released when the cervix is stimulated.

Once the balloon is inserted and your baby’s well-being has been assessed using the fetal monitor, you’ll be able to move around and perhaps even go home if your doctor agrees. The medical team in place will let you know what to do next. You can expect the balloon to fall out on its own once your cervix has dilated to about 3 cm, which can take around 12 hours. The medical team may also pull on the balloon occasionally to see how things are progressing and determine whether it’s ready to fall out.

Oxytocin

If no other method works, the doctor will use oxytocin to induce contractions artificially. Oxytocin is a hormone that’s naturally secreted by the body to stimulate labour. In the hospital, you’ll be given an artificial version of this hormone intravenously.

Administering oxytocin is generally done to produce moderate to strong contractions (i.e., 45 to 60 seconds long, every 3 minutes). Once this is achieved, the oxytocin dose will remain stable as long as labour progresses adequately and the baby is doing well. Sometimes, oxytocin triggers quick and intense contractions.

If you receive oxytocin, two sensors connected to a monitor will be attached to your belly. One sensor will be used to monitor your baby’s heart rate, the other to observe your contractions. Many hospitals have portable or wireless monitors that allow the mother to move around.

Alternative methods to speed up labour

Certain natural methods are believed to induce labour. So what do we know about their effectiveness?

• Sexual intercourse
  In theory, sexual intercourse near the end of pregnancy may induce labour for several reasons. For one, nipple stimulation and orgasm may lead to the production of oxytocin, which could subsequently cause contractions. In addition, the prostaglandins present in sperm might have a beneficial effect on the cervix. However, studies regarding the effectiveness of using sexual intercourse to induce labour have yielded conflicting results. This method is also not recommended for women with ruptured membranes or an active genital infection. Nonetheless, sex remains safe during pregnancy.
• Nipple stimulation
  Research shows that nipple stimulation is beneficial when it comes to inducing labour. This method is believed to release oxytocin into the bloodstream naturally, therefore causing the uterus to contract. The nipples can be stimulated in several ways: by massaging the breasts, rolling the nipple between the fingers, or using a breast pump. Some midwives recommend stimulating your nipples several times a day. Just be careful that they don’t become irritated, red, or chapped. It’s also best to stop once your contractions are less than 3 minutes apart.
• Castor oil
  Castor oil is thought to act on the uterus because of certain substances it contains. Research shows that it may increase the likelihood of labour starting within 24 hours of use. However, castor oil causes many unwanted side effects, such as nausea, intestinal pain, and diarrhea. In addition, some midwives believe castor oil should be contraindicated if the baby’s head isn’t pressing against the cervix or if the cervix is still very thick. Castor oil could then cause the membranes to rupture without inducing labour. For this reason, it’s important to keep in mind that using castor oil is not without danger and should always be done under medical supervision.
• Evening primrose oil
  Evening primrose oil contains ingredients that function as precursors for prostaglandin synthesis, which may help induce labour. Few studies regarding the effectiveness of this oil to trigger labour have been carried out, and those that have don’t offer any convincing evidence that it works.
• Acupuncture and homeopathy
  At this time, there is no convincing evidence that acupuncture and homeopathy are effective ways to induce labour. Therefore, professionals don’t typically suggest them.

Things to keep in mind

• Sometimes labour needs to be stimulated or induced.
• Many methods can help accelerate the labour process.
• Ask your medical team about the advantages, disadvantages, and contraindications of each one.

Scientific review: Roxanne Piché, nursing adviser, Maternal Fetal Medicine Clinic, CHU Sainte-Justine Research and copywriting: The Naître et grandir team Updated: September 2021

Photo: 123rf/Sakhorn Saengtongsamarnsin