Induction of labor refers to the use of medications or other methods to induce, or cause, labor. This practice is used to make contractions start so that delivery can occur.

Cervix is the elongate inferior end of the uterus where it connects to the vagina.

The Uterus and Cervix

The uterus is the muscular organ that nourishes and supports the growing embryo (see Figure). Its average size is approximately 5 cm wide by 7 cm long (approximately 2 in by 3 in) when a female is not pregnant. It has three sections. The portion of the uterus superior to the opening of the uterine tubes is called the fundus. The middle section of the uterus is called the body of uterus (or corpus). The cervix is the narrow inferior portion of the uterus that projects into the vagina. The cervix produces mucus secretions that become thin and stringy under the influence of high systemic plasma estrogen concentrations, and these secretions can facilitate sperm movement through the reproductive tract.

Several ligaments maintain the position of the uterus within the abdominopelvic cavity. The broad ligament is a fold of peritoneum that serves as a primary support for the uterus, extending laterally from both sides of the uterus and attaching it to the pelvic wall. The round ligament attaches to the uterus near the uterine tubes, and extends to the labia majora. Finally, the uterosacral ligament stabilizes the uterus posteriorly by its connection from the cervix to the pelvic wall.

This anterior view shows the relationship of the ovaries, uterine tubes (oviducts), and uterus. Sperm enter through the vagina, and fertilization of an ovulated oocyte usually occurs in the distal uterine tube. From left to right, LM × 400, LM × 20. (Micrographs provided by the Regents of University of Michigan Medical School © 2012)

National Cancer Institute (NCI)

Sometimes, a doctor or midwife might need to induce (bring about) labor. The decision to induce labor often is made when a woman is past her due date but labor has not yet begun or when there is concern about the baby or mother's health. Some specific reasons why labor might be induced include:

• A woman's water has broken (ruptured membranes), but labor has not begun on its own
• Infection inside the uterus
• Baby is growing too slowly
• Complications that arise when the mother's Rh factor is negative and her unborn baby's is positive
• Not enough amniotic fluid
• Complications, such as high blood pressure or preeclampsia
• Health problems in the mother, such as kidney disease or diabetes

The doctor or midwife can use medicines and other methods to open a pregnant woman's cervix, stimulate contractions, and prepare for vaginal birth.

Elective labor induction has become more common in recent years. This is when labor is induced at term but for no medical reason. Some doctors may suggest elective induction due to a woman's discomfort, scheduling issues, or concern that waiting may lead to complications. But the benefits and harms of elective induction are not well understood. For instance, we do not know if elective labor induction leads to higher or lower rates of cesarean delivery compared to waiting for labor to start on its own. Yet, doctors have ways to assess risk of cesarean delivery, such as a woman's age, whether it is her first pregnancy, and the status of her cervix. Elective induction (not before 39 weeks) does not appear to affect the health of the baby.

If your doctor suggests inducing labor, talk to your doctor about the possible harms and benefits for both mother and baby, such as the risk of c-section and the risk of low birth weight. You will want to be sure the benefits of inducing labor outweigh the risks of induction and the risks of continuing the pregnancy.

In most cases, induction is limited to situations in which there is a problem with the pregnancy or in which the pregnancy has continued past the infant's due date. It is usually best to "let the baby set the delivery date" and allow labor to begin on its own, unless there is a medical reason to do otherwise.

Women who want labor induction for non-medical reasons should discuss it with their health care providers.

Several weeks before labor begins, the cervix begins to soften (called "ripening"), thin out, and open to prepare for delivery. If the cervix is not ready, especially if labor has not started 2 weeks or more after the due date, a health care provider may recommend medication or other means to ripen the cervix before inducing labor.

Health care providers use a scoring system, called the Bishop score, to determine how ready the cervix is for labor. The scores range from 0 to 13. A score of less than 6 means that the cervix may need help to prepare for labor.

If the cervix is not ready for labor, a health care provider may suggest one of the following steps to ripen the cervix:

• Stripping the membranes. The health care provider can separate the thin tissue of the amniotic sac, which contains the fetus, from the wall of the uterus. This process causes the body to release prostaglandins (pronounced pros-tuh-GLAN-dins), which soften the cervix and cause contractions.
• Giving prostaglandins. This drug may be inserted into the vagina or given by mouth. The body naturally makes these chemicals to ripen the cervix, but sometimes additional amounts are needed to help labor occur.
• Inserting a catheter. A small tube with an inflatable balloon on the end can be placed in the cervix to widen it.

A change in the CERVIX UTERI with respect to its readiness to relax. The cervix normally becomes softer, more flexible, more distensible, and shorter in the final weeks of PREGNANCY. These cervical changes can also be chemically induced (LABOR, INDUCED).

Once the cervix is ripe, a health care provider may recommend one of the following techniques to start contractions or to make them stronger:

• Amniotomy (pronounced am-nee-OT-uh-mee). A health care provider uses a tool to make a small hole in the amniotic sac, causing it to rupture (or the water to break) and contractions to start.
• Giving oxytocin (also called Pitocin). Oxytocin is a hormone the body naturally makes that causes contractions. It is given to start labor or to speed up labor that has already begun.

A study found that, for healthy pregnancies, inducing labor after full term (39 weeks) rather than waiting for natural labor doesn’t increase the risk of major complications for newborns.

Being inside the womb for a full 39 weeks is important for a baby’s development. A baby’s brain nearly doubles in size during the last few weeks of pregnancy. The lungs and liver are still developing too.

Once a woman has reached full term, her doctor may suggest inducing labor for different medical, or non-medical, reasons. Sometimes the mother will request an induced labor if she’s uncomfortable in her final weeks.

Prior research has shown that inducing labor before 39 weeks of pregnancy puts the baby at risk of serious health problems. Researchers wanted to find out if inducing labor at full term also puts a baby at risk of serious health problems. They also wondered if it increases a woman’s chance of needing a surgery called a cesarean section, or C-section.

The team enrolled 6,000 pregnant women in the study. Participants were randomly assigned to two groups. Half of the women waited to have a natural labor. The other half were induced at 39 weeks.

The two groups of babies had similar survival rates and chances of serious health problems, such as needing help with breathing, having a seizure, or getting an infection. Inducing labor also reduced the mothers’ chance of a C-section and lowered their blood pressure.

“Induction at 39 weeks should not be routine for every woman, but it’s important to talk with their provider and decide if they want to be induced and when,” says study leader Dr. William Grobman of Northwestern University.

​​​​Let baby set the deliv​​ery date.

• You can avoid or reduce many health risks for the mother and the baby by waiting until 39 weeks of pregnancy to deliver, if there is no medical reason to deliver earlier.
• Research shows that the fetus goes through a significant amount of lung, liver, and brain development between 37 weeks and 39 weeks of pregnancy.
• Your due date could be off​ by up to 2 weeks, which means if you have your baby before 39 weeks you could actually be having it early.
• Research shows that delaying delivery until 39 weeks of pregnancy or later—if there is no medical reason to deliver earlier—is not associated with increased rates of stillbirths​.

Why should I wait until ​​at least 39 weeks of pregnancy to deliver?

• Babies born at or after 39 weeks of pregnancy face fewer health problems.
• Babies' brains, lungs, and liver continue important development until 39 weeks.

What are the risks to my baby and to me if I deliver without a medical reason before 39 weeks of pregnancy?

Risks to the baby:

• May need to stay in the neonatal intensive care unit (NICU)
• Birth complications, including breathing problems and cerebral palsy
• Developmental disabilities, such as attention deficit/hyperactivity disorder (ADHD)
• A 63% greater chance of death within the first year of life compared to babies born between 39 weeks and 41 weeks

Risks to the mother:

• Postpartum depression
• Stronger and more frequent contractions
• Need for a cesarean delivery and its outcomes, including risk of infection, longer recovery time, and the possible need for cesarean delivery in future pregnancies

What questions should I ask​ my health care provider?

• Are there any medical reasons that I might need induced labor before 39 weeks?
• What are the potential complications for my baby of elective induction?
• What are the potential complications for my own health?
• How do you tell when my body is ready for labor?​