An induction may be offered if it's felt that continuing the pregnancy poses a risk to your health or to the health of your baby. The most common reason for an induction is the continuation of a pregnancy beyond 41 or 42 weeks, in which case the placenta may begin to fail. Induction may be offered earlier if you have twins, or a medical condition such as diabetes. Before setting a date for induction, your doctor may offer to strip your membranes (see Stripping the membranes) to help you go into spontaneous labor.
Induction is not the same as an augmentation of labor, which is when drugs are used to increase the efficiency of your contractions when you've already gone into labor spontaneously (see Descent with contractions).
Before an induction, you'll have an internal examination to assess the cervix. Induction is easier if your cervix is short and soft, described as "favorable" or "ripe," rather than long and firm. The findings may be logged in a table called the Bishop's Score, which also assesses how far the cervix is dilated (see Dilation), the position of the cervix, and the station of the fetal head in the pelvis (see The station). A total score over six indicates good conditions for an induction of labor.
If your cervix isn't ripe, it can be softened with prostaglandins. These are naturally occurring chemicals that help stimulate contractions. Artificial prostaglandins can be given in the form of vaginal tablets of gel, which are placed at the top of the vagina near the cervix, or a vaginal suppository or an oral pill. This is usually effective, but sometimes prostaglandins fail to soften the cervix and may be tried again after a few days. On the other hand, some women experience dramatic effects after a small dose.
Amniotomy, or artificial rupture of the membranes (ARM), is one of the most important steps in the induction process, often referred to as "breaking the water" and it's done once the cervix is soft and slightly dilated, and the head has started to enter the pelvis. A thin plastic probe is passed through your cervix and used to make a small hole in the amniotic membranes, which allows some of the fluid around your baby to leak out. This softens the cervix even more and can provoke contractions in the muscular wall of the uterus. If contractions don't become established after ARM, then you'll require treatment with Syntocinon or Pitocin.
Oxytocin is a natural hormone that stimulates the uterus, increasing the frequency and strength of contractions. A synthetic form, Syntocinon or Pitocin, is used with the same effect. It's diluted in fluid then dripped into a vein in your arm or injected into a large muscle. This is safe and effective when used correctly; however, it must be used with care since excessive contractions can reduce your baby's oxygen supply in labor. Your contractions and your baby's heartbeat will be continuously monitored (see Monitoring During Labor).
If your labor is induced, the chance that you will need an assisted delivery with forceps or vacuum or a cesarean is increased. This is even more likely if you are having your first baby, if the cervix is unfavorable, or if you're being induced relatively early in your pregnancy. The reason for these medical interventions is usually that the labor is proceeding too slowly, or that it cannot be started at all, despite all of the steps taken. Also, concerns about the baby's well-being during the induction process can sometimes lead to intervention.
Some women find that they experience strong contractions very quickly after an induction. Since they haven't been able to build up gradually to more painful contractions, they may be less able to tolerate the pain, which can result in an increased need for stronger types of pain relief such as an epidural.