Induction of Labor: What You Need to Know



How can I make sense of what I hear about induction of labor?

What normally causes labor to begin?

What is the safest point in pregnancy for the baby to be born?

Why are so many women experiencing induced labor?



How can I make sense of what I hear about induction of labor?

Rates of labor induction are on the rise in the United States. This trend is fueled by increases in the number of women having high-risk pregnancies and more frequent use of labor induction for non-medical or social reasons (sometimes referred to as elective induction). There is confusion and disagreement about the safety and appropriate use of labor induction. As a result, use of induction varies widely from one caregiver or hospital to the next. Even the results of research studies on labor induction provide conflicting answers. It can be difficult to make informed choices about induction of labor in the midst of these uncertainties.

This section of the website contains research, information, and conclusions about labor induction:
  • Options: includes a look at the most common reasons caregivers recommend induction of labor and the alternatives to labor induction
  • Best Evidence: tells you which reasons your caregiver may recommend induction are supported by research evidence and which are not.
  • Tips and Tools: includes tips for avoiding an unnecessary induction of labor and for keeping you and your baby as safe as possible if induction is necessary.
  • Resources: provides resources for learning more about induction of labor.

What normally causes labor to begin?

Although the complex process that causes labor to begin is not fully understood, researchers believe that the most important trigger is a surge of hormones released by the fetus. This hormone surge, which prepares the lungs and digestive system for life outside the womb, signals the fetus's readiness for birth. In response to these signals, hormone receptors in the woman's uterus turn on and the muscles in her uterus change to allow her cervix, at the lower end of her uterus, to open. In short, when a woman goes into labor on her own, this is 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 reaches the "developmental milestone" of readiness for birth at a slightly different time. The most reliable sign that the baby is ready to be born safely is labor beginning on its own at full-term.

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. (You can find an estimated due date calculator on the Resources Page of this section.) However, more and more research shows that babies born between 37 weeks and 38 weeks and 6 days, whether labor started on its own or was induced, face a higher risk of several health problems than babies born from 39 weeks on. For this reason, labor induction or planned cesarean surgery should never be used before 39 weeks unless there is a clear medical reason. (The Best Evidence: Induction of Labor page describes the medical reasons for induction of labor.) Although the risk of stillbirth or newborn death is very low, this risk begins to rise around 41 weeks and rises significantly after 42 weeks. To prevent these rare deaths, most caregivers will offer induction of labor between 41 and 42 weeks.

Why are so many women experiencing induced labor?

Many medical, legal, social and financial factors influence the use of labor induction. These include:

Women's lack of knowledge about the risks, benefits, and appropriate use of labor induction.
  • A surprising number of women don't have accurate information about how long a normal pregnancy should last. A study of new mothers found that nearly one in four believed that a baby was full-term when it reached 34-36 weeks, and more than half believed it was safe to deliver the baby at that point. In fact, it is unsafe to deliver a baby before 39 weeks unless there is a clear medical need.
  • Childbirth education classes that teach specific information about the risks, benefits, and appropriate uses of labor induction reduce the number of women having induced labor. However, attendance at childbirth education classes appears to be decreasing in the United States, and childbirth education classes are getting shorter, leaving less time to address this important topic.

Lack of shared decision making about induction.
According to the Foundation for Informed Medical Decision Making, shared decision making is the process by which a health care provider communicates to the patient personalized information about the options, outcomes, probabilities, and scientific uncertainties of available treatment options and the patient communicates her values and the relative importance she places on benefits and harms.
  • Many women who agree to induction lack information about the reason they are being induced. It is also common for a woman to believe labor is being induced for a medical reason, even though there is no solid research to support induction in that situation.
  • In the Listening to Mothers II survey, more than half of women whose labors had been induced were unable to correctly answer basic questions about the safety of labor induction.

The perception among women, caregivers, and hospital administrators that induction of labor is convenient and cost-effective.
  • The ability to schedule labor onset seems appealing on many levels. It enables women to arrange household support or childcare and maximize the amount of maternity leave they have available after the birth of the baby.
  • Caregivers can arrange their schedules more easily when they don't have to attend births at unpredictable times.
  • Hospitals can plan for staffing more easily when they know how many women will be in labor on a given day.
  • Despite these common perceptions, elective induction of labor can result in neonatal intensive care admission and can increase the length of the hospital stay and the overall cost of care. In addition, elective induction, especially in first-time mothers, frequently results in c-section which exposes mothers to the risks of surgery, requires a longer recovery, and affects choices, outcomes, and costs in future pregnancies.

Frequent use of screening tests at the end of pregnancy, despite lack of evidence that the use of such tests improves outcomes.
  • Routine use of ultrasound and other fetal tests, especially in low-risk women, may unnecessarily raise the concern about fetal wellbeing and lead to induction of labor or even preemptive cesarean surgery. For example, ultrasound may raise the caregiver's suspicion that the baby is large or that the amniotic fluid level is low. Based on that suspicion, many caregivers will recommend labor induction, even though studies have shown that inducing for these reasons in otherwise normal pregnancies does not improve outcomes, and may increase the chance that the induction will end in a c-section.

The belief that the best way to manage risks in pregnancy is to deliver the baby.
  • Fortunately, it is uncommon in this day and age for a baby born at full-term to die around the time of birth or experience serious illness or injury. However, these outcomes still occur despite advances in obstetric and neonatal care. Doctors or midwives may recommend inducing labor as a way of lowering the chance of these problems happening. However, it is impossible to know which women should be induced because injury and death are often unpredictable. As a result, thousands of women may have labor induced to prevent just one injury or death, and all of those women and babies will be exposed to the risks of labor induction, which may include cesarean surgery, instrumental delivery (assisted by forceps or vacuum extraction), and newborn breathing problems.



References

Bricker L, Neilson JP, Dowswell T. Routine ultrasound in late pregnancy (after 24 weeks' gestation). Cochrane Database Syst Rev. 2008;(4)(4):CD001451.

Declercq ER, Sakala C, Corry MP, Applebaum S. Listening to mothers II: Report of the second national U.S. survey of women's childbearing experiences. New York: Childbirth Connection; 2006.

Goldenberg RL, McClure EM, Bhattacharya A, Groat TD, Stahl PJ. Women's perceptions regarding the safety of births at various gestational ages. Obstet Gynecol. 2009;114(6):1254-1258.

Lockwood CJ. The initiation of parturition at term. Obstet Gynecol Clin North Am. 2004;31(4):935-47.

Manzanares S, Carrillo MP, Gonzalez-Peran E, Puertas A, Montoya F. Isolated oligohydramnios in term pregnancy as an indication for induction of labor. J Matern Fetal Neonatal Med. 2007;20(3):221-224.

Mozurkewich E, Chilimigras J, Koepke E, Keeton K, King VJ. Indications for induction of labour: A best-evidence review. BJOG. 2009;116(5):626-636.

Simpson KR. Reconsideration of the costs of convenience: Quality, operational, and fiscal strategies to minimize elective labor induction. J Perinat Neonatal Nurs. 2010;24(1):43-52.

Simpson KR, Newman G, Chirino OR. Patient education to reduce elective labor inductions. MCN Am J Matern Child Nurs. 2010;35(4):188-94; quiz 195-6.

Simpson KR, Newman G, Chirino OR. Patients' perspectives on the role of prepared childbirth education in decision making regarding elective labor induction. Journal of Perinatal Education. 2010;19(3):21-32.


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Options: Induction of Labor

Most recent page update: 5/23/2011


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