Labour induction is one of the most common interventions in obstetrics. In fact, one in three pregnant women needs to be induced. And cervical ripening—preparing the cervix for childbirth—is one of its crucial steps.
There are many methods of cervical ripening, still, two of them are being used the most; mechanical and pharmacological. Both approaches are approved by national guidelines, but offer different advantages. Plus, within both groups, there are numerous options that you and your clinician can go for.
What is the history behind these? Which method is more popular? And what to keep in mind when choosing the right one for you?
A little bit of history
Cervical ripening, as part of the labour induction, has been around for a while. More structural approaches were first introduced into obstetrics as far back as the 18th century. In those early days, the methods were mechanical, but more invasive. These included practices such as administering a sponge tent or performing amniotomy—that means breaking the waters.
By the 20th century, with advancements in medical science, pharmacological methods became more popular.
Present day
Today, pharmacological methods are still used in most cases because clinicians are accustomed to them.
But the popularity of modern mechanical methods is constantly on the rise; more and more people opt for them for their gentle mode of action and safety profile, all while having similar efficacy. For both the mother and the baby.
Mode of action
So, what does the “mode of action“ mentioned earlier stand for? Basically, it’s the way in which mechanical or pharmacological methods ripen your cervix.
Mechanical methods open and soften the cervix physically, without using drugs. This may not sound that gentle, but in reality, it is quite the opposite. Mechanical approach mimics natural labour and can stimulate the release of prostaglandins that occur naturally in your body.
Pharmacological methods, on the other hand, work by releasing drugs—usually prostaglandins—to prepare the cervix. For example, synthetic prostaglandins soften your cervix and relax cervical muscles to help with dilation.
Examples of mechanical methods
Synthetic osmotic dilators
Cervical ripening with hygroscopic dilators can be traced back to ancient times. Originally, people would induce labour with naturally found materials such as Laminaria, seaweed stems that absorb liquid to expand.
These inspired the creation of a synthetic material that mimics their mode of action; a patented hydrogel, which is used to make DILAPAN-S, a modern osmotic dilator. The dilator is just a little bigger than a matchstick, and usually, clinicians administer several pieces into the cervical canal. Similarly to seaweed stems, DILAPAN-S absorbs fluids from your cervix to gently expand and make it soft, stretchy and open. It takes about 12–24 hours to prepare your cervix for childbirth.
If you want to know more about DILAPAN-S, click here.
Balloon catheters
In this method, a catheter (soft silicone tube) is inserted through the cervix behind internal os. Near the tip of the tube, there is a balloon filled with sterile saline. This exerts a pressure on your cervix, making it dilated.
There are two types of balloon catheters:
- Single catheter, or Foley catheter, only has one balloon positioned just beyond the internal cervical os (the opening that leads to your uterus). It typically stays in place for 12-24 hours. Originally, these were primarily used as urinary catheters made for emptying the bladder. Over time, they began to be applied in obstetrics—however, they are still not officially approved for cervical ripening.
- Double catheter has two balloons—one placed inside the uterine cavity (above the internal os) and the other in vagina (just outside the external os). This way, the pressure is applied to both ends of cervical canal, enhancing its dilation. The double balloon catheter generally stays in place for up to 12 hours.
Examples of pharmacological methods
Synthetic prostaglandins
Prostaglandins are natural hormones found in various tissues in your body. In labour, synthetic prostaglandins are administered to help in cervical ripening. They work in two major ways. They cause your cervix to soften, relax and open up, and they make the smooth muscles of your uterus contract—which helps with pushing the baby out during childbirth.
The two most common prostaglandins used for cervical ripening are dinoprostone and misoprostol. Dinoprostone can be administered in a few different ways—as a vaginal gel, tablet, or a pessary (a device that is inserted into your vagina, where it gradually releases the medicine). Misoprostol can be administered vaginally or used as a pill.
It’s important to note that you may need more than one round of cervical ripening.
Which method is for you?
When selecting the most appropriate option for you, your clinician can consult criteria such as: efficacy, safety, comfort/gentleness and versatility.
Efficacy
The term efficacy refers to how well a particular method of labour induction achieves the outcome—successful cervical ripening followed by vaginal delivery.
We can say that the most frequent pharmacological and mechanical methods are equally effective. But they do differ in some other aspects.
Safety
This criterion evaluates the potential risks and challenges, for the mother and the baby. These include, for example, uterine hyperactivity (painful or excessive contractions), fetal distress, systemic side effects, postpartum complications, and other issues.
Mechanical methods, such as DILAPAN-S, have generally better safety profiles. For example, they are less likely to cause uterine hyperactivity.
Comfort/gentleness
Comfort or gentleness considers how comfortable and tolerable the method is for the mother. It weighs in the possible pain, discomfort, a possibility to do daily activities, the need for repeated CTG, but also whether or not an outpatient (home-based) ripening is an option.
Higher comfort/gentleness makes the overall mother’s experience less stressful and more pleasant.
Based on recent clinical evidence, mechanical methods offer a higher level of comfort. For example, DILAPAN-S has a non-pharmacological, gentle mode of action. That means that the need for continuous screenings and other examinations is lower. There is a significantly smaller chance of it causing too many contractions or pain, so your clinician can even let you await your labour in the comfort of your home. What’s more, it provides you with greater freedom of movement—so you can relax in a way that suits you.
Versatility
Versatility refers to how usable the ripening method is for different mothers and in different situations.
Mechanical methods have the upper hand here as well. Because of their safety profile and gentleness, they can be used for most induced women—including those with, for example, previous C-sections.
Making an informed choice
Understanding the different methods of cervical ripening is crucial. Both mechanical and pharmacological methods are approved by NICE guidelines, but they do have their differences. When deciding on the method, you and your clinician can discuss four key criteria—efficacy, safety, comfort/gentleness and how suitable the method is for you. Although pharmacological methods are still more frequent these days, the popularity of mechanical ripening is rising because of its gentle mode of action and safety for mothers and their babies.
