Induction of labor is a medical procedure that uses artificial methods to start labor contractions before they begin on their own. It’s one of the most common interventions in pregnancy, and it’s performed when continuing the pregnancy poses more risk to the mother or baby than delivering. About 1 in 4 pregnancies in the United States involves some form of labor induction.
Why Labor Is Induced
Induction is recommended when specific medical conditions make waiting for spontaneous labor unsafe. The most common reasons include preeclampsia (dangerously high blood pressure during pregnancy), gestational diabetes, low amniotic fluid, restricted fetal growth, and going past your due date. If your water breaks but contractions don’t follow, induction is also typical.
The timing depends on the condition. For preeclampsia without severe symptoms, induction generally happens at 37 weeks or at diagnosis if caught later. For severe preeclampsia, it may happen as early as 34 weeks. Late-term pregnancies, those reaching 41 weeks without labor starting, are routinely induced to reduce the risk of stillbirth and other complications. Infections of the amniotic membranes and placental separation from the uterine wall are situations where induction happens urgently, regardless of gestational age.
Elective induction at 39 weeks, meaning induction without a specific medical reason, has also become more common. The American College of Obstetricians and Gynecologists recognizes 39-week elective induction as a reasonable option after a discussion between you and your provider about the benefits and risks.
How Your Cervix Is Assessed First
Before induction begins, your provider checks whether your cervix is ready for labor using a scoring system called the Bishop score. This score evaluates five things: how dilated (open) the cervix is, how thin it has become, how soft it feels, its position, and how far the baby’s head has descended into your pelvis. Each factor gets a point value, and the total ranges from 0 to 13.
A score of 6 or less means your cervix isn’t ready yet and will likely need help softening and opening before contractions can be effective. A score above 8 suggests favorable conditions for induction, especially if you’ve given birth before. This distinction matters because it determines which induction method your provider will use and how long the process might take.
Cervical Ripening: Preparing for Contractions
When the Bishop score is low, the first step is cervical ripening, which is the process of softening and thinning the cervix so it can dilate. There are two approaches: medication-based and mechanical.
Medication-based ripening uses prostaglandins, which are hormone-like substances that soften cervical tissue and can trigger mild contractions. These come as a gel or a thin insert placed near the cervix. Side effects can include nausea, vomiting, diarrhea, and fever. The main risk is overstimulation of the uterus, where contractions become too strong or too frequent. Prostaglandins are generally not used if you’ve had a previous cesarean section because of the elevated risk of uterine rupture.
Mechanical ripening uses a small balloon catheter inserted through the cervix. The balloon is inflated with saline, and the gentle pressure encourages the cervix to open. In studies of this method, about 47% of women spontaneously expelled the catheter as their cervix dilated, and roughly half began contracting on their own without needing additional medication. The balloon approach is considered very safe, particularly for women who’ve had a prior cesarean. One study found a 40% vaginal delivery rate using this method alone in women with a previous cesarean and an unripe cervix, with no cases of uterine rupture.
Starting and Sustaining Contractions
Once the cervix is favorable, the next step is stimulating regular contractions. The standard method is a synthetic version of oxytocin, the hormone your body naturally produces during labor. It’s delivered through an IV and gradually increased until contractions come every two to three minutes.
The goal is to mimic the natural labor pattern. Your provider adjusts the dose based on how your body responds and how the baby is tolerating contractions. Fetal heart rate monitoring runs continuously throughout an induced labor so the care team can catch signs of distress early.
In some cases, your provider will also break your water manually, a quick procedure called amniotomy. This releases prostaglandins naturally and allows the baby’s head to press directly on the cervix, which can speed things along.
What the Experience Feels Like
Induced labor can feel different from spontaneous labor. Contractions often come on more quickly and with less buildup, which some women describe as more intense than the gradual onset of natural labor. The entire process, from the start of cervical ripening to delivery, can take anywhere from several hours to two or more days, depending on how ripe your cervix was at the start.
If your cervix was already favorable, induction with oxytocin alone may lead to delivery within the same day. If you started with an unripe cervix, expect a longer timeline. Cervical ripening alone can take 12 to 24 hours before active labor even begins. Pain management options like epidurals are fully available during induced labor, and many women request one earlier in the process because of the faster onset of strong contractions.
Induction doesn’t guarantee a vaginal delivery. If labor doesn’t progress despite adequate contractions, or if the baby shows signs of distress, a cesarean section may be needed. The likelihood of this depends heavily on factors like your Bishop score at the start, whether you’ve given birth before, and the reason for induction.
Other Medical Meanings of Induction
The term “induction” appears across several areas of medicine, each using it to describe the initial, intensive phase of a treatment or biological process.
Cancer Treatment
In cancer care, induction refers to the first phase of chemotherapy designed to eliminate as many cancer cells as possible and push the disease into remission. For acute leukemia, this phase typically lasts 4 to 8 weeks and involves multiple chemotherapy drugs, sometimes including injections of medication directly into the fluid surrounding the spinal cord to prevent cancer from spreading to the brain. If the cancer carries a specific genetic marker called Philadelphia chromosome, a targeted drug is added alongside chemotherapy. The induction phase is followed by additional rounds of treatment aimed at keeping the cancer from returning.
Organ Transplantation
After an organ transplant, induction immunosuppression is the aggressive, short-term use of drugs to prevent the immune system from attacking the new organ in the critical period right after surgery. These medications work by depleting or blocking the specific immune cells most responsible for organ rejection. Over time, patients transition to lower-dose maintenance medications they’ll take long-term.
Developmental Biology
In embryology, induction describes how one group of cells signals another group to change its fate during development. Signaling cells release chemical messages that tell neighboring cells what type of tissue to become. This process is how a single fertilized egg develops into an organism with hundreds of distinct cell types, with groups of cells essentially instructing their neighbors through waves of molecular signals that pattern the entire body.