Induction of Labor (Labor Induction)

Overview of Induction of Labor

Inducing labor, or kick-starting the childbirth process artificially, has become a common practice. Since 1990, we’ve seen a near doubling in the number of labor inductions. However, there’s a considerable variation worldwide with how often labor is induced, depending on different guidelines and confusion over best practices. In wealthier countries, it’s estimated that around 25% of babies are born after an induced labor. However, this figure is typically lower in less wealthy countries. This piece will discuss the reasons for inducing labor, any potential risks, complications, and different methods of induction.

Anatomy and Physiology of Induction of Labor

The uterus is made up of two parts: the body and the cervix. The body section is mostly smooth muscle while the cervix is largely made up of a protein called collagen. During pregnancy and childbirth, the cervix undergoes several changes including becoming shorter, thinner, and wider to allow for the baby to pass through.

There are methods to help induce labor, meaning to start it artificially, if it doesn’t begin naturally. These methods can be mechanical or involve the use of medication. Both techniques aim to trigger the changes in the cervix that happen naturally during labor, making it easier for childbirth to take place.

Why do People Need Induction of Labor

Deciding when to deliver a baby can depend on several factors related to the mother’s medical and obstetrical history. The process of inducing labor, or IOL, may be chosen if it’s believed to produce better outcomes for the mother, the baby, or both, compared to just waiting for labor to start naturally. The American College of Obstetricians and Gynecologists gives several guidelines on when to consider delivering a baby in different situations.

Here are a few examples of when it might be best to deliver:

• If the mother has low amniotic fluid (oligohydramnios), it’s usually best to deliver between 36-37 weeks of pregnancy.
• If the baby isn’t growing normally in the womb but the umbilical cord blood flow is normal (fetal intrauterine growth restriction with no abnormal Doppler), typically delivery should happen between 38-39 weeks.
• If blood flow via the umbilical cord is completely absent (fetal intrauterine growth restriction, with absent end-diastolic flow), the baby might need to be delivered earlier, around 34 weeks.
• In case the blood flow is reversing, indicating severe problems (fetal intrauterine growth restriction, with reversed end-diastolic flow), childbirth may be required around 32 weeks.
• If the mother has chronic high blood pressure (hypertension) but is not on medication, delivery usually should occur between 38-39 weeks.
• If the mother has temporary high blood pressure due to pregnancy (gestational hypertension), generally delivery is suggested at 37 weeks.
• If the mother has pregnancy-induced high blood pressure with more severe symptoms (preeclampsia with and without severe features), again delivery may need to take place at 37 weeks or earlier, around 34 weeks.
• If the mother has diabetes before getting pregnant and it is well-managed (pregestational diabetes), normally delivery is recommended between 39 weeks.
• If the mother develops diabetes during pregnancy and manages it through diet or exercise (gestational diabetes), delivery is usually advised between 39-40 weeks.
• If the mother’s water breaks too early (preterm prelabor rupture of membranes), delivery might be necessary as soon as it happens, but not before 34 weeks.
• If the pregnancy is more than a week past the due date (late-term), birth will usually be induced between 41 weeks.

In some cases, labor might be induced because of sudden and severe conditions, like placental abruption (abruptio placentae), infection of the tissues surrounding the fetus (chorioamnionitis), or the baby dies while in the womb (intrauterine fetal demise). Sometimes, inducing labor might be chosen for logistic reasons such as the distance from the hospital, the risk of labor progressing too quickly, or certain mental and social disorders. If the baby’s lungs are mature enough, this can also be a reason to induce labor, though this should typically not happen before 39 weeks unless there are other medical reasons.

When a Person Should Avoid Induction of Labor

There are certain situations where induced labor (IOL) is not recommended. These may include:

– Vasa previa or placenta previa: This is where the baby’s blood vessels or placenta cover the mother’s cervix and can lead to complications during labor.

– Transverse fetal presentation: This is when the baby is lying sideways in the womb instead of the normal head-down position, making natural birth difficult.

– Umbilical cord prolapse: This occurs when the umbilical cord drops into the birth canal ahead of the baby, which can cause serious problems.

– History of a prior classical cesarean section: If the mother has had a specific type of cesarean section before, known as a classical cesarean section, induced labor may not be safe.

– Active herpes infection: Moms with an active herpes outbreak can pass the infection to their baby during a vaginal birth, so induced labor may be unsafe.

– A previous myomectomy breaching the endometrial cavity: If the mother has undergone surgery (myomectomy) to remove fibroids (non-cancerous growths in the uterus) that has entered the inner lining of the uterus (endometrial cavity), it might not be safe to induce labor.

Equipment used for Induction of Labor

Inducing labor, or starting childbirth, can usually be done with two main methods: mechanical and intervention with drugs. There’s a rating scale, called the Bishop score, that doctors use to measure how ready your cervix is for labor. If the score is less than 8, the cervix may not be ready for labor, and doctors will use a method called cervical ripening.

Cervical ripening is how doctors prepare the cervix for labor. Mechanical cervical ripening can be done with a small medical balloon, like a Foley catheter or Cook catheter, which is put into the cervix. Other tools, like osmotic dilators, laminaria, and synthetic dilators can also be used and are placed in the cervix.

Drugs can also be used to start labor. The drugs, such as prostaglandins, work to ripen the cervix. Certain types of prostaglandins, like Misoprostol and Dinoprostone, can be used in different amounts and ways, but doctors need to be careful with women who’ve had certain types of cesarean delivery because of risks to the uterus.

Oxytocin is another drug often used; it’s given through an IV in varying amounts. Sometimes doctors will also break the water bag, or amniotic sac, in a process called amniotomy, along with these methods to start labor.

Who is needed to perform Induction of Labor?

When you’re in the hospital having a baby, there’s a whole team of professionals taking care of you and your newborn. This team is made up of nurses, midwives (who are experts in normal pregnancy, childbirth, and newborn care), resident doctors, obstetricians (doctors specialized in pregnancy and childbirth), anesthesiologists (doctors who help manage your pain), neonatologists (doctors who specialize in newborn babies), pediatricians (doctors for children), and lactation services (experts who help with breastfeeding). The entire team works together to make sure both you and your baby are safe and well-cared for during labor and after birth.

It’s also important to have an obstetrician who is trained and ready to perform a cesarean section (or C-section, which is a surgical procedure used to deliver a baby) available at all times when labor is being induced. This is in case there’s a sudden need for a C-section. These doctors are always ready for any possible changes in the condition of a mother or baby to ensure their safety.

Preparing for Induction of Labor

When it’s time to deliver a baby, doctors use something called a Bishop score to evaluate how ready the mother’s body is. This score evaluates different aspects such as the opening of the uterus (dilation), the softness of the uterus (consistency), the thinning of the uterus (effacement), the baby’s position, and the baby’s head’s placement in relation to the pelvis (station). Scoring systems like this are used in the last part of the third trimester and during a process known as Induction of Labour (IOL), which is when labor is artificially started. When a woman has a high Bishop score (8 or more), they are more likely to deliver their baby vaginally. However, if the score is low (3 or less), it could mean that a vaginal delivery is less likely.

Before starting the IOL, it is key that women understand what it involves, its benefits, and possible risks both for them and the baby. Some of the risks are similar to when labor happens naturally; these can include the need for an emergency cesarean section (a surgical delivery of the baby), complications leading to an operative vaginal delivery, infection (chorioamnionitis), issues with the baby’s heart rate, and heavy bleeding after delivery (postpartum hemorrhage). It’s important that every woman considers these potential issues before deciding on having an IOL. In some cases, even after the IOL process has started, if the opening of the uterus (cervical dilation) doesn’t keep on progressing, it might be necessary to do a cesarean section. Therefore, it’s recommended that you wait 12-18 hours after your water breaks (amniotomy) before moving forward with a cesarean delivery.

During the process of planning an IOL, doctors will inform you about various methods to start the labor. This could involve mechanical methods (like inserting a small balloon into the uterus to help it dilate) or medications that stimulate contractions (pharmacological methods). Sometimes, these methods are used together to help induce labor. Different studies have compared these induction methods and have found that using a balloon is as effective as using a medication called vaginal PGE2 but with the balloon method, it tends to be safer for the baby. One other medication called oral misoprostol can induce labor but it might be slightly less effective than a balloon catheter, plus it’s also less clear if there’s a difference in safety outcomes for the baby.

Before agreeing to IOL, it’s crucial to understand the potential need for a cesarean section. Cesarean section rates have been heavily discussed in medical literature and socially. Recent studies have shown that women who had an elective IOL at 39 weeks of pregnancy (choosing to start labor without a medical reason) had lower rates of cesarean section and no significantly worse outcomes for the baby. Another previous study also found that women being induced were not at a higher risk of severe tears or needing an operative vaginal delivery, regardless of how far along they were in their pregnancy.

If a mother needs to be induced for a specific medical reason, such as a small baby (fetal growth restriction), she might be concerned about risks to the baby (neonatal risks). Previous studies have shown no change in the risk of the baby’s death, needing intensive care, or difficulty with breathing, regardless of how far along she was in her pregnancy or how many times she had given birth before. However, other research suggests that for babies delivered at 37 weeks of pregnancy, there might be higher rates of complications compared to those delivered at 38 and 39 weeks of pregnancy.

How is Induction of Labor performed

There are several methods to start labour if it doesn’t begin naturally, a process known as induction. One method is mechanical dilation using a Foley catheter, a double-balloon catheter, or a device called laminaria. For a Foley catheter, this small tube with a balloon at the end is inserted through the opening of your womb, known as the cervix. The balloon is then filled with a safe salt water solution. This puts pressure on your womb, encouraging it to open or dilate to allow for childbirth. It has been found that filling up the balloon more results in quicker induction.

The double-balloon catheter works similarly, but this time there are 2 balloons – one that applies pressure to the inside of your womb and another that does the same to the external part. Both of these balloons can be filled with various amounts of the same safe salt water solution. These devices are typically removed once your womb has opened about 3 to 4 centimeters in preparation for childbirth. Osmotic dilators, which are devices that help to open your womb, are also available in different sizes and can be placed into the opening of your womb.

Cervical ripening with misoprostol is another method of induction. This drug can be taken in a range of ways, such as orally, through your vagina, or sublingually (which means under your tongue). Different doses can be used, usually ranging from 25-50 micrograms. If labour is being induced due to a loss of a baby in the uterus during the second trimester, higher doses of hormones can be administered, up to 400 micrograms every 3 hours for a maximum of 5 doses.

The hormone PGE2 (dinoprostone) is also available and can be used as a vaginal insert or as a gel. The dosages differ depending on the form – the gel contains 0.5 mg, and the insert contains 10 mg. Another common hormone used for induction is syntocinon, which is given via an IV. The dosing is often adjusted so that the contractions are 2 to 3 minutes apart, leading to the opening or dilation of your womb. Depending on the hospital, there may be a limit on the dose of oxytocin (another name for syntocinon) a pregnant woman can receive if she has had a previous cesarean section.

Once your womb has opened, a procedure called amniotomy can be performed with an “amnio hook”. This procedure involves breaking the water bag that surrounds and protects your baby in the womb to further encourage labour. Several factors, like the baby’s position in the womb, whether the baby’s head is engaged for delivery, your preference and pain levels, among other things, are taken into account before it’s done.

Possible Complications of Induction of Labor

There is a growing trend of women choosing to induce labor and often the reasons for doing so are not emergencies. The safety of induction methods is increasingly important, even if it means they might not be as effective. Mechanical methods, such as using a balloon catheter, could be better than drug-based methods. They are commonly available, less costly, and could have fewer side effects, like causing the womb to contract too much (also known as uterine hyperstimulation). This could be safer for the baby because if contractions are too long or very close together, the baby may not receive enough oxygen.

Inducing labor with drugs can cause a condition called uterine tachysystole, where there are more than 5 contractions in 10 minutes. This could lead to the baby’s heart rate slowing down, this is known as fetal decelerations or bradycardia. Much has been written about the risks of uterine tachysystole when prostaglandins, a type of hormone, are used to induce labor.

Other potential complications include bleeding during labor, presence of the baby’s first stool in the amniotic fluid (indicating the baby is stressed), the umbilical cord slipping out ahead of the baby (cord prolapse), pain that isn’t relieved with regional anesthesia, tearing of the area between the vagina and rectum (perineal lacerations), heavy bleeding after birth (postpartum hemorrhage), infection of the amniotic fluid (chorioamnionitis), and infection of the lining of the uterus after birth (postpartum endometritis).

What Else Should I Know About Induction of Labor?

Induction of labor (IOL) is a procedure that can be used to help control when a pregnant woman gives birth in order to improve the health of the mother or the baby. Many studies have been done, and are still ongoing, to make sure this technique is safe for both mother and baby. Some of these studies are examining if IOL affects the number of cesarean sections (C-sections, which is a type of surgery used to deliver a baby). The highest quality studies are needed to look at how satisfied and safe mothers and babies are after IOL.