Cervidil is a small vaginal insert that slowly releases a synthetic version of prostaglandin E2, a hormone your body naturally produces during labor. Its job is to soften and thin out the cervix so it’s ready to dilate, a process called cervical ripening. It’s typically used when labor needs to be induced but the cervix hasn’t started preparing on its own.
How Cervidil Softens the Cervix
Your cervix is made largely of collagen, the same tough structural protein found in tendons and skin. For labor to progress, that dense collagen network needs to break down so the cervix can stretch. Cervidil works by mimicking the prostaglandin E2 your body would normally ramp up on its own near the end of pregnancy.
Once the insert begins releasing the drug, it triggers a cascade of changes in the cervical tissue. Enzymes called matrix metalloproteinases increase, and these enzymes directly degrade collagen fibers. At the same time, the prostaglandin draws white blood cells (particularly neutrophils) into the cervix. Those immune cells release their own collagen-breaking enzymes, amplifying the softening effect. The result is a cervix that goes from firm and closed to soft, thinned out, and more easily dilated.
Beyond breaking down collagen, prostaglandin E2 also stimulates mild uterine contractions. These aren’t the strong, regular contractions of active labor. They’re more like early warm-up contractions that help move the process along. In many cases, cervical ripening with Cervidil is enough to kick-start labor on its own. If it isn’t, the softened cervix is now ready for the next step, usually an IV medication called oxytocin or breaking the water manually.
When Cervidil Is Used
Providers assess cervical readiness using a scoring system called the Bishop score, which rates the cervix on a scale of 0 to 13 based on how dilated, thinned, and positioned it is. A score below 6 means the cervix isn’t ready for labor. Cervidil is designed for exactly this situation: it bridges the gap between an unripe cervix and one that can respond to stronger labor-inducing methods.
Common reasons for induction include going past your due date, pregnancy complications like high blood pressure, or concerns about the baby’s growth. When the cervix is already favorable (Bishop score of 6 or higher), providers can often skip ripening agents and move straight to oxytocin or membrane rupture.
What the Insert Looks Like and How It’s Placed
Cervidil is a thin, flat insert about the size of a small rectangle. It contains 10 mg of dinoprostone (the pharmaceutical name for prostaglandin E2) embedded in a time-release polymer. Rather than delivering the full dose at once, the insert releases the medication gradually at a controlled rate over the hours it stays in place. A long, thin retrieval tape extends from the insert and stays accessible so the device can be pulled out quickly when needed.
A provider places the insert in the posterior fornix, the space behind the cervix at the back of the vaginal canal. You’ll typically be asked to lie down for a period after placement so the insert stays positioned correctly. From there, your baby’s heart rate and your contractions are monitored continuously or at regular intervals.
Timeline: How Long It Takes
In clinical trials, the median time from Cervidil placement to the onset of labor was about 12 hours for first-time mothers and roughly 7 hours for women who had given birth before. Those are medians, meaning half of patients took longer and half went faster. Some women begin having regular contractions within a few hours, while others need the full duration or additional interventions afterward.
The insert can stay in place for up to 12 to 24 hours depending on how the cervix responds. If ripening is insufficient in that window, providers will discuss next steps, which may include a second round of cervical ripening or a different approach. Once the insert is removed, there’s a required waiting period of at least 30 minutes before oxytocin can be started, because combining the two raises the risk of overly strong contractions.
Why the Retrieval Tape Matters
One of Cervidil’s key advantages over other cervical ripening options is reversibility. Because the insert is a physical device with a retrieval tape, it can be removed in seconds if problems arise. Once removed, the drug’s effects begin to wear off relatively quickly.
This is a meaningful difference compared to oral or vaginal tablets used for the same purpose. A tablet dissolves and can’t be taken back. If it causes too many contractions or the baby shows signs of distress, there’s no way to simply pull it out. With Cervidil, the retrieval system gives providers a reliable off switch. The insert is removed immediately if any of the following occur:
- Uterine hyperstimulation: contractions that are too frequent, too long, or too intense
- Fetal distress: changes in the baby’s heart rate pattern that suggest the baby isn’t tolerating the contractions well
- Labor begins: regular, painful contractions occurring every three minutes or less
- Membranes rupture: your water breaks on its own
- Maternal side effects: nausea, vomiting, low blood pressure, or rapid heart rate
Possible Side Effects
The most closely watched side effect is uterine tachysystole, a term for the uterus contracting too frequently (more than five times in a 10-minute window). In clinical trials of 320 women who received Cervidil, about 4.7% experienced tachysystole without any signs of fetal distress, and about 2.8% experienced it alongside concerning changes in the baby’s heart rate. Both rates were significantly higher than in the placebo group, where tachysystole with fetal distress occurred in only 0.3% and tachysystole without fetal distress didn’t occur at all.
These numbers are relatively low, but they’re the reason continuous fetal monitoring is standard during Cervidil use. When tachysystole does happen, removing the insert typically resolves the problem. Other side effects like nausea and cramping can occur but tend to be mild.
What You Can Expect During the Process
After the insert is placed, you’ll likely stay in bed for a short period. Most hospitals then allow you to get up for bathroom trips and limited movement, though policies vary. You’ll have monitoring equipment tracking the baby’s heart rate and your contractions, which can restrict how far you can move from the bed.
Many women describe the early hours with Cervidil as a waiting game. You may feel mild cramping or period-like discomfort as contractions begin. Some women sleep through much of the process, while others find the cramping too uncomfortable to rest. The intensity varies widely from person to person. If the insert works well and labor kicks in, the contractions will gradually become stronger and more regular. At that point, the insert comes out and labor management shifts to the next phase, whether that means oxytocin, breaking the water, or simply letting labor continue on its own.