What causes labour?The exact mechanisms causing labour in pregnant mothers are uncertain. However, it is very likely that there is a series of events involving various hormones, genes and other substances within your body, resulting in the dual process of contractions in the womb and opening of the neck of the womb (cervix). It is also believed that this is initiated by the baby and the placenta.What is induction of labour (IOL)?You may have heard this term many times, but do you know what it means? Induction of labour (IOL) is any medical intervention performed that stimulates the onset of labour pains (i.e. to establish labour), aiming to result in the delivery of the baby vaginally (read the article on Stages of Labour).Do I really need to undergo IOL?A variety of medical conditions may arise during the course of your pregnancy that may put you or your baby’s well-being at risk. This may necessitate your doctor offering you an early delivery of your baby. In certain instances where you or your baby is assessed to be unable to tolerate the stress of labour, a cesarean section may be suggested to expedite your delivery instead. Only if time permits and there is no immediate danger to you or your baby, an IOL can then be offered.What are the medical reasons that may necessitate IOL?These can be broadly categorized into conditions that can put either you or your baby at risk should the pregnancy be allowed to progress. Under such a circumstance, your doctor would have investigated you thoroughly and assessed that it would be safer for either mother or baby that the delivery occurs before your due date or in rarer cases, even before maturity is reached.
Are there any non-medical reasons for IOL?
It is important to note that routine IOL in uncomplicated pregnancies has not been successful in reducing stillbirth rate and results in higher rates of forceps, vacuum and cesarean deliveries.Are there any risks to an IOL?As with any procedure, there are certain concerns associated with an IOL. They include:
As such, an IOL is only performed when the benefits of a delivery outweigh the above-mentioned risks or when your obstetrician is confident that the risks associated with IOL can be adequately minimised by appropriate precautionary measures.When am I considered unsuitable for an IOL?IOL is not performed when you are deemed unsuitable for a vaginal delivery in the first place. They include conditions such as a low-lying placenta, breech or transverse lie of the baby.If you have had one previous cesarean section, an IOL is generally not advised as the risk of a uterine rupture is approximately 2.5%. This is five times higher than the risk of uterine rupture should you go into spontaneous labour on your own, and is considered to be unacceptable by many.How is an IOL performed?Labour starts when the cervix initially soften, shortens and dilates (read the article on Labour Pain Relief). This can be achieved through the insertion of prostaglandin, a hormone, into the vagina. Locally, the pessary known as Prostin is commonly used. Once the cervix is adequately dilated and effaced (thinned out), the membranes can be ruptured and an oxytocin infusion (another hormone) can be started to maintain the labour contractions.Prostaglandin application vaginally
Rupture of membranes and oxytocin infusion
Myths surrounding induction of labour (IOL)Myth 1: The patient suffers some pain from the time the prostaglandin is introducedThis is not necessarily true. Some patients may experience mild pain while the cervix is responding slowly to the prostaglandin. In this instance, she is encouraged to ambulate.Myth 2: IOL is ‘more painful’ than normal labourThere is no scientific evidence to support this myth. One reason for this perception is that a successful IOL will bring on the labour pains. The inevitable negative association leads to the negative perception.Myth 3: IOL is unnaturalThere is nothing unnatural about going through a labour brought about by an IOL. Once labour is established (read the article on Stages of Labour), the same rules on progress of labour apply.Explore more
By Dr TAN Thiam Chye, Dr TAN Kim Teng, Dr TAN Heng Hao, Dr TEE Chee Seng John,KK Women’s and Children’s HospitalSources:The New Art and Science of Pregnancy and Childbirth, World Scientific 2008.