The decision to induce labour is not made lightly. The chance is doubled that extra pain relief, forceps delivery or caesarean section will be needed. Since the ideal outcome is a healthy baby and mother after a normal vaginal delivery, a doctor wants to be sure induction is absolutely necessary before going ahead. There are times when induction is a proper decision. Some of the reasons are listed in the sidebar.
Most labour inductions are done for the sake of the baby’s health. There is often a choice to be made between inducing for the baby’s health or waiting for the baby to mature inside a little longer. Sometimes those extra days can prevent the problems of prematurity. A baby who is not growing adequately is often better off outside the womb where growth can be assured. If there is not enough amniotic fluid around the baby or other testing shows that the baby is no longer receiving the blood supply needed from the placenta, labour may need to be induced.
Towards the end of pregnancy, changes occur to the placenta that affect its ability to work properly. Since the baby needs the placenta for oxygen and nourishment, a poorly functioning one can be stressful for the baby. The added effect of labour, which reduces blood supply to the placenta for a minute at a time every three minutes, can lead to distress in the fetus. This is why most doctors choose to induce labour once a woman has reached 41 weeks of pregnancy. The placenta should still be working well enough to allow the baby to tolerate labour
Other times when it is considered better to induce labour than to wait include blood type incompatibilities (where the mother’s immune system tries to destroy the baby’s blood cells) and twin-to-twin transfusions (where one twin is receiving a much larger blood supply from the placenta than the other is). Also, if there are signs of infection inside the womb, the baby needs to be delivered as soon as possible.
When inducing labour for the mother’s health, the baby’s health is also a factor. A number of medical disorders may lead to induction of labour. Some may have been present before pregnancy such as heart conditions, lung diseases and diabetes. Women who develop high blood pressure in pregnancy are at risk of seizures, bleeding disorders, kidney failure and liver failure. Vaginal bleeding may mean the placenta is separating from the wall of the uterus, a threat to both mother and baby.
Sometimes a woman enters the early phase of labour having regular contractions that soften and thin the cervix but does not proceed into active labour. Other times the membranes rupture but the woman still does not enter into active labour. This can go on for days and the woman does not receive enough rest or nourishment. Induction may be indicated for these women.
Inducing labour because it is more convenient to deliver at a certain time is not a good idea but there may be special circumstances. For instance, if a woman has a history of rapid delivery in the past and lives a long distance from the hospital, induction may be planned. This will reduce the likelihood of her delivering by the side of the road on the way to the hospital. The mother, father and doctor need to discuss these situations to be sure that the risks of induction are outweighed by the special circumstances involved.
One of the factors that can affect a successful induction is the state of the cervix. The cervix is the structure at the bottom of the uterus that keeps the baby inside. For most of the nine months, the cervix is long, hard and closed. When the time is right, it then suddenly changes to allow the baby to pass by and out the birth canal. At this time it is considered favorable or ripe.
If induction is necessary and the cervix is not favorable, there are methods that can be used to help change this condition. By inserting something into the cervix, it can be stretched. Often a catheter with a balloon tip is used for this. The use of a medical compound called prostaglandin gel in the cervix or the vagina can also result in these changes. Either of these methods can result in the onset of labour. If the cervix is favorable, it is appropriate to proceed to induction. Sometimes all that is needed is to rupture the membranes (break the waters) to cause labour to begin. Oxytocin infusion (“the drip”) has been used for years to try to establish labour.
More recently, one or two doses of prostaglandin gel placed in the vagina has been found to be effective and more acceptable to women. These medications both stimulate the body’s own natural hormones that lead to labour contractions. There are times when all three methods are used. Regardless of the method chosen, labour may still take several days to start.
On rare occasions, these medications may lead to contractions that are too strong or too long for the baby to tolerate. If this happens, another medication may be given to reverse the effects. This allows time to turn off the oxytocin, remove the prostaglandin or do an immediate caesarean section. Women receiving oxytocin are also more likely to request epidural analgesia. Fetal heart rate monitoring is often used to assess the effects on baby. An intravenous (IV) line is usually set up so treatment can be given rapidly, if necessary.
Labour induction has a certain number of risks. When labour needs to be induced for the health of mother and baby, there is a choice of methods. The cervix must be assessed to determine if it has changed enough to improve the chances of a successful induction. If the cervix is not ready, cervical ripening or pre-induction must precede the induction. The goal of induction is to have the healthiest baby and mother possible at the end of the procedure.