Methods to Promote Cervical Changes for Induction of Labor

By: Aunt Doula (10/22/2022)

Interventions to induce or augment labor can happen during spontaneous labor or to begin a planned induction of labor. There are specific methods and medications used in both scenarios and typically occur in a predictable order. Depending on your facility, one method or another may not be practiced, or only one medication type may be available. Listed here are the cervical induction possibilities so that you are aware if they are offered to you, but know that they may not be offered at your facility or country.

The first goal post of labor becoming truly established occurs in the cervix. The cervix must be readied for labor and this means it must soften, thin, and open in order for the baby to exit the uterus for a vaginal delivery. Early labor with mild to moderate contractions assist the cervical changes, however if the cervix is hard, thick and closed, strong contractions will not be able to advance the baby or the labor - the cervix is the doorway of delivery and it must be ready to release before the labor can progress. Prostaglandin administration can lead to contractions, as the cervical changes are directly linked to the process of labor, however it is likely that you may require the second step of induction which is Pitocin to induce regular and strong contractions to reach active labor and maintain through transition and pushing stages.

Cervical changes have separate medical terms for softening, thinning and opening, so you may hear words such as 'ripening' 'effacement' and 'dilation' during the early stages of labor. Cervical 'ripening' is the softening of the cervix. Cervical 'effacement' is the thinning of the cervix. Cervical opening is the 'dilation.'

In order to induce cervical changes artificially, there are prostaglandin hormone analogs that mimic the prostaglandins released during spontaneous labor. These can be administered or triggered multiple ways and each has their benefits, drawbacks, facility limitations and clinical application for your situation.

Two hormonal analogs are commonly used, however in the United States only one is approved by the FDA for effecting cervical changes for labor induction. Known by its brand name "Cervadil" it is also known as Dinoprostone and PGE2. The other analog that is used 'off label' for induction is known by its brand name "Cytotec" also known as Misoprostol and PGE1.

Cervadil is typically administered as a 'pessary' or vaginal insert that is akin to a tea bag, inserted into the vagina and directly contacts the cervix for the medication to be absorbed through the cervical tissues. It has the distinct advantage that if the pregnant person has too strong a reaction to the Cervadil (such as tachysystole where the uterus has contractions without a break in between) the pessary can be removed. Other forms of Cervadil include a gel, however this cannot be removed and has to be applied appropriately.

Misoprostol is used in multiple ways and as it is 'off label' for induction in the US, but is approved in the EU. There is little consistency among facilities and providers for using oral pills or vaginal application. Taking misoprostol orally allows for pulsed and low dosages to be given, however it has been shown in studies to induce cervical changes less than direct application to the cervix. Cervical application of the pill is difficult to properly dose as the pill must be broken into multiple pieces in order to cover the cervix and leads to inconsistent coverage. In approved countries misoprostol can be available as a gel with the same appropriate application required.

Mechanical methods also exist to open (dilate) the cervix and attempt to trigger natural releases of prostaglandins. Using a foley catheter balloon or cervical dilating rings, the cervix is encouraged to open with pressure from inflating the balloon or inserting progressively larger rings. This achieves two potential goals - The first of which is to mimic the pressure on the cervix that happens during spontaneous labor caused by the top of the baby's head pressing internally when engaged in the pelvis. The Foley balloon or cervical rings being slowly inflated or inserted mimics this pressure and sends the signal to release prostaglandins which are an important part of opening the doorway of labor. The second potential goal is that the dilation being induced by the cervix being pressed open will hopefully continue and encourage the thinning, softening and opening as the prostaglandin releases occur.

It used to be considered that Cervadil had better outcomes and less side effects to misoprostol in certain clinical applications, however more recent studies have not been finding that to be a repeatable outcome, so choosing between the two should be a discussion with your provider and take all of your specific indications into consideration before you choose one or the other.

Once the cervix has begun to soften, thin and open, the second step of induction begins - Pitocin Administration for Labor Induction and/or Augmentation