It’s Almost Time: The Facts about Inducing Labor

Your baby is almost here! Now, it’s time to start preparing for his or her entry to the world. Sometimes, though, the baby doesn’t seem quite as willing to leave your body as you are ready to meet him or her. In these cases, the doctor might speak to you about inducing labor. In the United States, one of the most common procedures performed in obstetrics is inducing labor before the mother starts the labor process on her own. But we know that you probably have some questions about why or how the process starts – and that even though labor is induced all over the country at every time of the day, you might still feel a little anxious about it.

Before scheduling you for induction of labor, your physician, or midwife should review your medical history and prenatal records, examine your cervix to make sure that you are a candidate for induction. This includes confirming the gestational age of your baby, estimating the size of baby and chances of complications occurring, and making sure that baby is in the vertex position (head down).

When will a doctor induce labor?

The decision to induce labor1 is made for two reasons:

  1. The induction is medically necessary, making delivery more beneficial to both mom and baby. Common situations include:
    1. the mother is a diabetic or gestational diabetic
    2. the mother has high blood pressure (primary hypertension, gestational hypertension, or preeclampsia)
    3. the presence of oligohydramnios
    4. the mother is overdue
  2. There are no medical conditions present to justify the induction, making the decision to induce labor is elective.

Your physician or midwife will explain the induction process to you, how long the induction may take (some inductions take several days), as well the possibility of needing a cesarean section to deliver your baby.

Medical necessity vs. elective induction

If you are being induced for medical reasons, such as high blood pressure or diabetes, it may be safer for you and your baby for delivery to happen sooner, rather than later.

There are a few situations where elective induction may be beneficial to you and baby, such as:

  • You live far away from the hospital
  • You had a fast labor with a previous pregnancy

Overall, however, the American College of Obstetricians and Gynecologists does not recommend this practice. Elective inductions are not without risks to you and your baby; therefore, your physician or midwife should inform you of the risks, allowing you to make an informed decision. You may develop chorioamnionitis due a prolonged period of time between rupture of membranes and delivery, or see increased bleeding after delivery (postpartum hemorrhage). You may also be “forced” into a Cesarean section if this is your first pregnancy and your cervix is not considered “ripe.”

Talk to your physician, or midwife regarding the benefits, as well as potential problems that may arise. Both ACOG and the American College of Nurse Midwives encourage patients to be involved in decisions made regarding their pregnancies, and delivery of their babies. By discussing the possible risks of procedures with you, your physician, or midwife, is practicing what is called informed consent.2

The Modified Bishop Score

The Modified Bishop Score is a tool used by obstetricians and midwives to determine whether or not your cervix is ready for labor. A high Bishop score (8 or higher) means that your cervix is ripe, and you have a similar likelihood to have a vaginal delivery if you are induced that you would have if you went into labor on your own. If the Bishop score is low (6 or lower), it is less likely that you will have a successful vaginal delivery.

modified bishop score

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The scoring is based on:

Cervical dilatation, or the distance that the cervix is opened

  • Closed (not dilated)- 0 points
  • Dilated 1-2 centimeters- 1 point
  • Dilated 3-4 centimeters- 2 points
  • Dilated 5-6 centimeters- 3 points
dilation-of-cervix

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Effacement, or the thickness of the cervix. The thinner (more effaced) the cervix is, the greater the score.

  • 0 to 30% – 0 points
  • 40-50%- 1 point
  • 60-70%- 2 points
  • 80% or more- 3 points
effacement

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Consistency, or the texture of the cervix.

  • Firm (hard and rubbery) – 0 points
  • Medium (not hard, but not soft) – 1 point
  • Soft (mushy) – 2 points

Position of the cervix in relation to your baby’s presenting part (part of baby’s body entering the birth canal) and your pelvis.

  • Posterior (in the back) – 0 points
  • Mid (in the middle) – 1 point
  • Anterior (in the front) – 2 points
position-of-cervix

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Station, which refers to how far, or how many centimeters, the baby has moved down into your pelvis in relation to your ischial spines (the bony projections in the lower pelvis). The lower the baby’s head, the higher the score. Until the baby has reached 0 station, the largest part of his head has not entered into your bony pelvis. Once this occurs, the baby’s head is engaged into the pelvis. The station will be documented in negative numbers until the head is at 0 station. When baby’s head moves past 0 station, the stations will be documented in positive numbers.

  • 0 Station: Baby’s head is at the level of your ischial spines
  • 1 Station: Baby’s head is approximately 1 centimeter above the ischial spines
  • 2 Station: Baby’s head is approximately 2 centimeters above the ischial spines
  • 3 Station: Baby’s head is approximately 3 centimeters above the ischial spines
  • 4 Station: Baby’s head is approximately 4 centimeters above the ischial spines
Ischeal Spine

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Drug-free options for ripening the cervix

++Amniotomy is the breaking the bag of water that has surrounded your baby throughout your pregnancy. The procedure is usually no more painful than a vaginal exam. A plastic hook that looks like a large crochet hook is used.

amniotomy

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In order for an amniotomy to be performed, your cervix must be dilated (open) to some extent. Before your physician or midwife breaks your water, he, or she, should perform a vaginal exam to make sure that baby is in the vertex position (head down), and baby’s head is pressing against your cervix. This is necessary to prevent a prolapsed cord. The labor and delivery nurse should document your baby’s heart rate before, and again after the procedure is performed, as well as the color of the amniotic fluid.

It is common for an amniotomy to be performed while you are receiving Pitocin. An amniotomy should not be performed if you have been diagnosed with placenta previa.

Once your membranes are ruptured (water is broken) the protective barrier from infection is gone, meaning bacteria may travel upward from the vagina to the uterus. Because of this, the labor and delivery staff should monitor your temperature on a regular basis, usually every hour. If you develop a fever, your physician or midwife should be notified.

Medications used to ripen the cervix

In situations where induction of labor is planned when the cervix is not favorable, your physician or midwife may use medications to soften the cervix, making the chances of a successful induction (one that ends with a vaginal delivery) more likely. It is not uncommon for these medications to cause contractions, which sometimes starts the labor process.

Prostaglandin E2s are often used when the cervix has not yet thinned out. This medication is inserted into the vagina and placed against the cervix. This normally occurs in the labor and delivery unit where your baby’s well-being and your contraction pattern can be closely monitored.

  • Prepidil (dinoprostone) is a gel that is placed inside of the cervix. Your physician or midwife will insert the gel and you will be asked to remain in bed for at least 30 minutes afterwards. This process can be repeated every 6 hours. You should receive no more than three doses within a 24-hour period.
  • Cervidil is another form of dinoprostone used to ripen the cervix. In this form, the medication is released more slowly than the above form. Unlike Prepidil, Cervidil is only inserted one time. This is a small, fabric sac that has a string attached to it. It is placed high in the vagina by the cervix. The string will hang from the vagina, making it easy to remove. You will be asked to remain in bed for at least 2 hours after the Cervidil has been placed. It will remain in the vagina for 12 hours. If you go into labor before the 12 hours (which sometimes happens), it will be removed sooner.
  • Pitocin (Oxytocin) is a hormone that is produced by the hypothalamus and secreted by the pituitary gland. It is the hormone that causes a pregnant woman to have contractions. A synthetic (man-made) form of oxytocin is given through intravenous infusion to induce labor. The use of oxytocin is one of the most common ways of inducing labor.
  • ++Misoprostol (Cytotec) is a Prostaglandin Misoprostol is actually a medication that is used to prevent peptic ulcers. Its use for ripening the cervix is what is known as an “off-label use.” It has not been approved for the purpose of ripening the cervix, but the ACOG recommends it, and considers it to be safe. There are two ways that it can be used: orally or through vaginal insertion. Current research shows that women that receive Cytotec to ripen the cervix are less likely to need oxytocin (Pitocin) to induce labor.1

Important information about, and side effects of, prostaglandins

If you don’t go into labor and the Cervidil is removed in 12 hours and the intravenous medication, Pitocin (oxytocin) may be started 30 minutes after it is removed.1 Cervidil and Prepidil should not be used in combination with oxytocin (Pitocin).

One side effect of prostaglandins is uterine tachysystole (contractions are too close). When the uterus contracts, the result is a decrease in blood supply to the baby. The ACOG defines tachysystole as more than five contractions in a period of 10 minutes. For this reason, you should be connected to monitor that displays your baby’s heart rate pattern, as well as your contraction pattern. If Cervidil is used and tachysystole occurs, it can be quickly removed by pulling on the string. In cases where the gel was used, irrigation of the vagina will wash it out.

Both prostaglandin preparations should not be used if you are already in labor. Also, they should not be used if your membranes are ruptured (your water is broken), or if there is abnormal vaginal bleeding. They should be used with caution if you have a history of asthma, or if you have been diagnosed with glaucoma.

Before inserting either Cervidil, or Prepidil, your baby’s heart rate pattern should be evaluated (by electronic fetal monitoring). If decelerations are present, they should not be inserted. If at any time after they are inserted, there are any problems with the baby’s heart rate pattern, they should be removed and steps should be taken to correct the problem with baby’s heart rate pattern. 

Cervidil and Prepidil should not be used if you have had 6 or more babies who were full-term at time of delivery, or if you have delivered a previous baby by cesarean section, or have had any surgery on their uterus. There is risk of uterine rupture in these cases.

Compared to Prepidil and Cervidil, uterine tachysystole (more than 5 contractions in a 10-minute period of time) occurs more often with Misoprostol, but current research shows that its use has not increased the rate of cesarean deliveries due to its use. There is a reduced risk of tachysystole if Misoprostol is given by mouth (orally).

Misoprostol does increase the risk of the baby having his first bowel movement before birth (meconium-stained amniotic fluid).

Let’s talk about Pitocin

Pitocin is delivered at a very precise dosage by an intravenous infusion pump. The dosage, or rate, of delivery (in milliunits per minute) is low at first and increased at regular intervals until contractions occur at a regular frequency. Hospitals are required to have a written protocol for the administration of Pitocin for induction of labor. The purpose of the protocol is to minimize the chance of errors regarding the dosage, as well as reduce the complications that may be caused by Pitocin.

When a pregnant woman is receiving Pitocin for induction of labor, a continuous, electronic fetal monitor should be used to measure the frequency of contractions and monitor her baby’s heartrate pattern.

When Pitocin is used for induction of labor, it is very important that the labor and delivery staff monitor baby’s heart rate pattern and the frequency of contractions. When a contraction occurs, it temporarily interrupts the amount of blood that flows reaches baby. Through a process called fetal circulation, oxygen is delivered to baby through the blood that flows through the umbilical cord, which normally has two arteries and one vein. Sometimes, a baby’s umbilical cord only has one artery and one vein (2-vessel cord). The umbilical vein carries red blood cells that contain oxygen and other nutrients from the placenta to baby. The arteries carry blood from back to the placenta. This blood contains carbon dioxide (the gas we breathe out), as well as other waste products that are produced by baby’s body. The carbon dioxide is transferred from the placenta, into your bloodstream and to your lungs, where it leaves your body when you exhale. The waste products are transferred to your bloodstream, where they are removed along with the waste products from your body.

Approximately 17 to 20 ounces of blood flows to the uterus every minute. From the uterus, most of this blood travels through the intervillous space from the placenta, through the umbilical vein, to the baby. In order for enough blood to reach the intervillous space, it must first flow through your spiral arteries. If there is not enough blood flowing through the spiral arteries into the intervillous space, your baby does not receive enough oxygen.

Chemoreceptors, which are located in baby’s cardiovascular system, are very sensitive to

a decrease in the supply of oxygen. When the chemoreceptors sense that the oxygen supply has been reduced, they respond by stimulating the vagal nerve, which alerts the baby’s cardiovascular system to reduce the heart rate. When the heart rate is lowered, the amount of oxygen being used is less. Every baby responds to this interruption of blood flow differently. How your baby responds to the temporary decrease in oxygen supply is determined by the fetal heart rate pattern that is shown on the electronic fetal monitor.

Risks of Pitocin induction

The main risks to both mom and baby when Pitocin is used for induction of labor are directly related to the rate, or dose, of the medication. The effects on the baby are related to the frequency of mom’s contractions. For this reason, the frequency and duration of the contractions must be monitored to prevent a negative effect on baby.3 The risks to the mother when Pitocin is used for induction of labor include uterine tachysystole (contractions are too close together), which, in rare cases, could cause the uterus to rupture (rip apart).

If contractions are too close together (tachysystole) and the fetal heart rate pattern shows that baby is unable to tolerate the contractions, the Pitocin infusion should be stopped immediately. The mother should be turn to her left side. An oxygen mask should be placed on the mother, and the rate of her primary intravenous fluid rate should be increased for a short period of time. These steps performed to correct the abnormal fetal heart rate pattern before baby develops hypoxemia If these measures do not reduce the frequency of contractions, a tocolytic medication should be given to the mother. After baby’s fetal heart pattern returns to normal, the Pitocin infusion may be restarted.

If baby shows signs of difficulty due to contractions, even if they are not too close together, the Pitocin infusion should be stopped, the mother turned on her left side, an oxygen mask placed on her face, and the rate of her primary intravenous infusion increased for a period of time.

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  1. Wing, D. (2016). Induction of labor. UpToDate. Retrieved from http://www.uptodate.com/contents/induction-of-labor
  2. Simpson, K. (2014). Patient education for elective induction of labor. Clinical Obstetrics & Gynecology, 57(2), 415-426. doi: 10.1097/GRF.0000000000000025
  3. ACOG Practice Bulletin No. 107 (2009): Induction of labor. Journal of Obstetrics & Gynecology, 114(2), 386-397. doi: 10.1097/AOG.0b013e3181b48ef5f