There are many reasons a doctor may recommend inducing labour. Labour can be brought on in a number of ways, although not all methods are one hundred percent effective. Because inducing labour increases the risk of requiring an emergency caesarean, most doctors will only induce labour if it is medically necessary, much to the disappointment of many an impatient expecting mother.
Why induce labour?
Reasons for inducing labour in a woman whose pregnancy has reached full term may include:
Ruptured membranes without subsequent labour
If a woman's amniotic sac ruptures (her water breaks), but she doesn't go into labour within a reasonable amount of time, (usually 24 hours), her doctor will often induce labour to prevent infection.
If a baby is more than two weeks overdue, doctors will usually induce labour. This is in part due to the danger of giving birth to a very large baby, and partly because there's a risk of the placenta failing to nourish the baby as it ages.
Failing health of mother or baby
Heart disease, preeclampsia (a condition of pregnancy), and other health problems can lead doctors to believe that waiting for natural labour to begin isn't worth the risk to mother or child.
Although it can be very hard to measure the true size of a baby in utero, doctors will often induce labour if they estimate the full-term baby's size to be bigger than average. The rationale is that a bigger baby may actually be overdue because the previously given due date is wrong. Or that the child will be too large to pass through the birth canal safely if it is allowed to gain much more weight before birth.
How is labour induced?
There are several methods used by doctors to induce labour:
Stripping the membranes
Stripping the membranes is done by the physician in the office. It isn't considered the most effective way to induce labour, but it can work. It is done by inserting a gloved finger into the cervix and separating the amniotic sac from the cervix by running the finger between the sac and the cervix. Doing this can trigger the release of hormones that may kick-start labour. Unfortunately, it may produce nothing more than discomfort for the expecting mother.
Prostaglandins are hormones that soften, or ripen, the cervix. A doctor will insert a suppository or gel into the vagina to encourage dilation and effacement of the cervix.
Rupturing the membrane
Artificial rupture of the membranes, or "amniotomy", is done by inserting a hook resembling a knitting needle into the cervix. This amniohook punctures the amniotic sac. With the fluid that was surrounding the baby gone, the baby descends and makes better contact with the cervix, while also triggering hormones that can precipitate labour. If labour doesn't begin soon after rupturing the membranes, further steps will be taken.
Pitocin is the synthetic version of oxytocin, the hormone that triggers uterine contractions. Administering pitocin is the last step in medical induction of labour. Pitocin is delivered by an intravenous tube in incrementally increasing amounts to mimic the release of oxytocin during natural labour.
What if inducing labour doesn't work?
The methods above can fail to bring on labour within a reasonable amount of time. When this happens, the only alternative is to perform an emergency caesarean section.