Induction of labour is the artificial initiation of labour before its spontaneous onset. Induction rates vary widely across British Columbia but roughly 15-30% of all mothers have their labour induced. Across Canada, induction rates average approximately 20%. The most common reason for inducing labour is post-dates pregnancy (pregnancy extending beyond 41 weeks).
Given the high rate of induction in Canada, it is important for expectant mothers to have an understanding of the risks and benefits of induction. Before inducing labour, physicians have a legal obligation to discuss its risks and benefits and to allow their patient to make an informed choice. Whether induction is offered as an option, its relative risks and benefits will depend on each individual woman’s circumstances. However, there are some general principles that the Society of Obstetricians and Gynaecologists of Canada (SOGC) have outlined.
Indications and Contraindications
First and foremost, induction carries risks; as a result, it should only be done when there is a convincing and compelling reason. There are many compelling reasons for a care provider to offer induction. Some examples include suspected fetal compromise, significant maternal disease not responding to treatment, and pregnancy extending beyond 41 weeks. Convenience (for the patient or the care provider) is not considered by the SOGC to be a convincing reason for inducing labour. A large baby (unless the mother is diabetic) is also not considered to be an acceptable reason to induce labour.
There are also clinical situations where induction should be specifically avoided. These situations include abnormal fetal presentation, significant prior uterine surgery, active genital herpes, and pelvic structural deformities. For women who have had a prior caesarean section, the type of incision will affect whether induction of labour is appropriate. In this situation, the SOGC recommends that the prior surgical report should be obtained to confirm that the previous incision will not create undue risk for the patient.
Benefits and Risks of Induction
The primary benefit, and goal, of induction of labour is to allow a mother to give birth as naturally as possible.
This benefit must be balanced against the known risks of induction. Induction of labour can increase the risk of caesarean section, as well as the risk of the use of forceps or vacuum, and can also increase the risk of failure to achieve labour. There is an increased risk of chorioamnionitis (a bacterial infection that can occur before or during labour), excessively frequent uterine contractions (which can affect the baby’s heart rate), and rupture of the uterus (a very serious obstetrical emergency). When the mother’s membranes are artificially ruptured, induction is associated with an increased risk of umbilical cord compression during labour, which cuts off the baby’s oxygen supply. Induction also increases the risk of inadvertently delivering a premature infant when fetal age has not been accurately dated.
Induction of labour may be the right choice for an expectant mother. However, since it is associated with some serious risks, expectant mothers should ensure that they have a thorough discussion with their physician to ensure they understand the reasons why induction is being recommended in their unique circumstances, as well as the specific risks and benefits that apply to the mother and her baby.