Labor Induction Basics
What is labor induction?
Labor induction is when a maternity care provider uses artificial ways, like artificial hormones instead of those produced by the mother, to cause labor to start before it starts on its own (spontaneous onset of labor). Scientists do not fully understand how labor begins on its own, so methods used to induce labor are directed at only part of the complex process. For instance, the commonly used induction drug Pitocin is an artificial version of oxytocin, a hormone that causes contractions. But contractions are not always enough to cause labor, so other methods may also be used. These include other hormone medicines, methods to stimulate women's own hormones, mechanical opening of the cervix and breaking the bag of waters.
Most use of drugs or other medical procedures for labor induction does cause labor to begin. However, attempts to induce labor do not lead to labor with about one woman in four, a situation that often ends in cesarean birth.
What causes labor to begin?
Researchers believe that the most important trigger of labor is a surge of hormones released by the fetus. In response to this hormone surge, the muscles in the mother’s uterus change to allow her cervix (at the lower end of her uterus) to open.
In other words, when a woman goes into labor on her own, it’s a powerful signal that her baby is ready to be born and that her body is ready for labor.
What is the safest point in pregnancy for the baby to be born?
Just as infants reach developmental milestones — like rolling over or crawling — at different times, every baby is ready to be born at a slightly different time. The most reliable sign that the baby is ready is when labor starts on its own and mom has reached full-term pregnancy (39 or more weeks).
Full-term has traditionally been defined as any time between 37 and 42 weeks of pregnancy, with your estimated due date at 40 weeks near the middle of this window.
However, more and more research shows that babies born during the 37th and 38th weeks of pregnancy, whether labor started on its own or was induced, face a higher risk of several health problems, compared with babies born at or after 39 weeks of pregnancy. Therefore, labor induction or planned cesarean surgery should never be used before 39 weeks unless there is a clear medical reason.
Though still low, the risk of stillbirth or newborn death begins to rise around 41 weeks (“late term”) and rises significantly after 42 weeks (“post term”), so most maternity care providers will offer to induce labor in women approaching 42 weeks.
Why might my care provider recommend induction?
You care provider may recommend induction of labor for a few reasons:
- Your provider expects pregnancy complications. In a small number of pregnancies, there could be problems that threaten your health, your baby’s health or both. For example, if you develop preeclampsia (high blood pressure in pregnancy), induction of labor can protect you and your baby from serious illness or even death.
- You have a preexisting medical problem. If you have chronic health problems before pregnancy, such as heart disease, diabetes or certain autoimmune diseases, you and your care provider may consider induction to prevent any complications related to these conditions.
- You’ve developed some other risk factor. Your care provider may recommend induction because a risk factor has developed. A risk factor is not a true complication or disease, but is a test result, clinical observation or other factor that increases the chance of health problems or labor complications. Examples include ruptured membranes (broken water) before labor, which may increase the chance of infection; pregnancy that has reached 41 weeks; and your provider’s suspicion that the baby is large, which may increase the chance of difficult labor or newborn injury. It’s important to understand that induction may or may not lower your risk based on these factors, so be sure to understand all the risk and benefits ahead of time.
- There are other non-medical reasons. Some caregivers offer induction, or agree to a woman's request for induction, for reasons other than health. For example, a care provider may offer induction on a day that she or he will be on call so you give birth with your familiar provider.
The Research and Evidence page will tell you which of these common reasons are backed by solid studies, and which have been disproven or need clearer research. This information will help you speak with your care provider and make wise decisions if labor induction is suggested.
Why might a woman choose induction when there is no clear medical reason?
Research suggests that inducing labor without a medical reason increases the risk of problems during and right after birth. Despite these risks, many women have labor induced for non-medical reasons. These include:
- Desire to get the pregnancy over with. This is most common non-medical reason women ask for or agree to an elective induction. Aches and pains, sleep problems and emotional ups and downs are common in the final days and weeks of pregnancy. Although induction of labor may seem like the best option for dealing with these problems, try coping with support or less risky medical interventions.
- Preference for a certain care provider. Most care providers share the responsibility of being "on call" for births with one or more other care providers. You may strongly prefer one care provider over the others, or fear that you will end up with a care provider you don't know. However, choosing labor induction is likely to have a much greater impact on your labor than having a particular care provider in the room. In most settings, nurses provide most care during labor. It’s also common for labor induction to take longer than a typical care provider's time on call, so you could end up beginning your induction with one person but giving birth with a different one anyway.
- Convenience. It's not easy to predict when labor will begin and that can make it tough to plan ahead and prepare for baby’s arrival. Since induction for convenience could result in health problems for you or your baby, it’s best to prioritize safety over convenience.
Why are so many women experiencing induced labor?
According to birth certificates, 23 percent of women who gave birth in 2013 had labor induction. This is our “official” national rate. However, studies to check the accuracy of this item have found that many actual labor inductions are uncounted on birth certificates.
Childbirth Connection’s national “Listening to Mothers III” survey, which polled women themselves about labor induction, is likely to provide a more accurate estimate of the induction rate. It also looked at many aspects of labor induction. Among participants, who gave birth in 2011-12, 41% reported that their care provider had tried to induce labor. They reported experiencing various drugs and procedures for this purpose. In most cases, the attempts to induce did start labor, which meant that, in all, 30 percent had medically induced labor. These women told us that their labors were induced for both medical and non-medical (convenience) reasons. Some of the “medical” reasons (for example, fetus might be growing quite large) are not supported by best research. Twenty-nine percent of the survey participants tried to start their labor on their own (self-induced labor). In a previous “Listening to Mothers” survey, about one in three who took this step told us that the reason was to try to avoid a medical induction.
As discussed in this section, induction is often chosen for non-medical reasons, even though it can increase risks for mom and baby. Here are some reasons the induction rate has been increasing in the United States:
- Women's lack of knowledge about the risks, benefits and appropriate use of labor induction. Not enough women have accurate information about when it is safe for a baby to be born. In our national “Listening to Mothers III” survey, we asked women when it would be safe to deliver a baby if there were no complications calling for earlier delivery. Just 21 percent chose the recommended 39 weeks or beyond, while 35 percent identified 37 or 38 weeks – a point still considered an early term birth with known risks to babies. And 44 percent identified more dangerous earlier weeks of pregnancy. One way women can get this information is by attending childbirth education classes; use these resources to find a class near you.
- Lack of shared decision-making about induction. Shared decision-making is when a woman works with her care provider to make an informed decision that is right for her. Through a decision tool or personal discussion, she learns about her options and the pros and cons of those options. She is helped to understand how her values and preferences might relate to the options. She gets help navigating the care system and increases the likelihood of safely receiving the care that is right for her. Unfortunately, not enough women who agree to induction actually have the information they deserve about why they are being induced, or falsely believe it is for medical reasons. Again, it is important for all women to learn as much as they can and to ask questions of their care providers before and during labor.
- The perception that induction is convenient and cost-effective. Despite the seeming appeal of being able to plan birth, elective induction can result in neonatal intensive care unit (NICU) admission and increase the length of the hospital stay and the overall cost of care. In addition, elective induction in first-time mothers and when the cervix is not soft and ready to open can result in C-section, which exposes mothers to the risks of surgery, requires a longer recovery and affects choices, outcomes and costs in future pregnancies.
- Overuse of unnecessary screening tests at the end of pregnancy. Routine use of ultrasound and other fetal tests, especially in low-risk women, may raise concerns about the baby’s health for no reason, leading to induction or even C-section when they are not needed.
- The belief that the best way to manage risks is to deliver the baby. Today, very few babies born at full-term die at birth or experience serious illness or injury. But this can still happen, and doctors or midwives may recommend inducing labor to lower the chance of these problems. However injury and death are often unpredictable and induction is not a proven way to prevent bad outcomes, whereas we know induction has its own risks (C-section in some groups of women, delivery by forceps or vacuum extraction, newborn breathing problems).
What factors affect whether I have an induction?
Your health needs and those of your baby can certainly influence whether you have an induction of labor, but some other key factors include:
- Your choice of care provider and birth setting.
- How determined you are to avoid induction that does not offer you or your baby clear health benefits.
Induction rates vary widely across hospitals and across different providers within a single hospital, often because providers differ in how they inform and support women at the end of pregnancy and in their judgment about when to recommend induction. Induction rates also vary from one birth setting to another due to differences in policies and practice styles. Because of this variation, your choice of care provider and choice of birth setting can have a big impact on your labor.
In addition, your commitment to letting labor begin on its own affects your chance of induction. It is common to have physical discomfort and emotional ups and downs at the end of pregnancy, but your baby needs these final days and weeks to prepare his or her lungs, digestive system and other organs for a safe transition to life outside the womb. Keeping this in mind can help you resist the temptation to induce labor for non-medical reasons.
Are there differences in when care providers recommend induction of labor?
Care providers may disagree about whether to induce labor in certain situations. These include:
- Prelabor rupture of membranes (PROM). If your water breaks and your pregnancy has reached full term (at least 37 weeks), this is a usually a sign that your labor is about to begin. For some women, labor contractions kick in within the first few hours, but for other women the process takes longer. If your water is broken for many hours, the risk of infection increases. Your care provider may suggest inducing labor to lower this risk, but providers may differ in how long they want to wait before inducing labor. Some may suggest inducing right away while others will wait 12 hours, 24 hours or longer. Your provider's recommendation may be based on his or her routine practice or your specific circumstances. If you choose to wait for labor to begin on its own, prevent infection by avoiding vaginal exams, sexual intercourse or placing anything in your vagina. Read what the research says about PROM and induction here.
- Pregnancy lasting beyond the estimated due date. Many women remain pregnant past their "estimated due date" at the 40-week mark. If a woman remains pregnant until 42 weeks or longer, the risk of stillbirth or newborn death increases significantly, so most care providers will recommend induction before 42 weeks. Some will recommend induction on the woman's due date or even earlier, while others wait until the woman is more than 41 weeks pregnant. Read what the research says about due dates and induction here.
- Your provider thinks you will have a large baby. A large baby may be more difficult to deliver, leading to a C-section or injury to the baby during vaginal birth (an uncommon outcome). However, studies have shown that inducing labor does not reduce the chance of newborn injury and, in fact, seems to increase the likelihood of a C-section. In addition, both ultrasound and hands-to-belly estimates of fetal weight are unreliable and often overestimate the baby's size. The baby’s actual weight can only be known after birth. Many babies delivered early because of suspicion that they are large are found to be in the normal range when born. Also, few women actually experience extra difficulty giving birth to larger babies. Waiting for labor is likely to be the safest approach.
Are the risks of induction higher for certain women?
Induction of labor is a major medical intervention that poses the potential for risk for all women and babies. That being said, risks can vary based on a few factors:
- Women having their first baby are more likely to have induction lead to a cesarean section than women who have given birth vaginally before.
- If the cervix has not already begun to thin out and dilate ("ripen"), or if the baby has not settled low in the pelvis, induction is more likely to lead to a C-section. A care provider can do a simple vaginal exam and calculate what is known as a "Bishop score" based on the qualities of the cervix and the baby’s position. A Bishop score below 6 (out of 13) signifies an increased likelihood that the induction will lead to a cesarean, whether or not medicines or other techniques are used to "ripen" the cervix.
- If the woman is less than 39 weeks pregnant, induction can result in a baby born with significant health problems, especially breathing difficulties. When labor is induced before 39 weeks, the baby is more likely to be admitted to the neonatal intensive care unit (NICU).
- Women who have given birth previously by cesarean section may face additional risks if labor is induced. Research suggests that risks are not higher with synthetic oxytocin (Pitocin) or if labor is induced before 41 weeks. However, the risk of having the woman’s previous C-section scar open during labor may increase if labor is induced after 41 weeks or if Prostaglandin E2 and misoprostol are used to induce labor. Some care providers or hospitals are unwilling to induce labor in women with past C-sections.