The Purpose of Cervical Ripening
For labor to progress, the cervix must first soften (effacement) and open (dilation). If a healthcare provider needs to induce labor before the cervix has naturally prepared, they will use a process called cervical ripening. This medical intervention can be necessary for various reasons, including post-term pregnancy, preeclampsia, or premature rupture of membranes (PROM). The medications used for this purpose are most commonly synthetic prostaglandins, which are hormone-like substances that help the body initiate these cervical changes.
What are the Medications Used for Cervical Ripening?
Several types of prostaglandin medications are used to help ripen the cervix, with the two most common being dinoprostone and misoprostol. While both serve a similar function, they differ in formulation, administration, and regulatory status.
Dinoprostone (Cervidil®, Propess®, Prepidil®)
Dinoprostone is a synthetic version of prostaglandin E2, a hormone naturally produced by the body during childbirth. It is available in several forms:
- Vaginal Insert (Cervidil® or Propess®): This is a small, flat device with a retrieval string, similar to a tampon. A healthcare provider places it next to the cervix, where it releases a controlled, low dose of dinoprostone over a period of 12 to 24 hours. Its primary advantage is that it can be removed easily and quickly if complications, such as uterine hyperstimulation, occur.
- Vaginal Gel (Prepidil®): This gel is inserted into the cervical canal via a catheter. It releases the medication more rapidly, and multiple applications may be needed.
Misoprostol (Cytotec®)
Misoprostol is a synthetic prostaglandin E1 analog. While it was originally developed for treating stomach ulcers, it is widely and effectively used off-label for cervical ripening and labor induction.
- Vaginal Tablet: A small piece of a misoprostol tablet is placed directly against the cervix by a healthcare professional. Repeat doses are often given every few hours. A key difference from the dinoprostone insert is that the tablet dissolves and cannot be easily retrieved once placed, making dose control less flexible.
How are These Medications Administered?
Administration of these medications is a medical procedure that must be performed by a trained healthcare professional in a hospital or clinical setting where continuous monitoring is available.
- Before Placement: A provider will first conduct a pelvic exam to assess the Bishop score, which evaluates the cervix's readiness for labor. They will also confirm the baby's position and perform fetal heart rate monitoring.
- During Placement: For a vaginal insert like Cervidil, the patient lies down while the device is placed in the vagina next to the cervix. For tablets like misoprostol, a quarter or eighth of a tablet is typically inserted vaginally.
- After Placement: The patient's uterine contractions and the baby's heart rate are continuously monitored for several hours to ensure safety. After the intended medication period, a healthcare provider removes the insert or assesses the cervix if a tablet was used.
Comparing Common Cervical Ripening Medications
| Feature | Dinoprostone (Cervidil®) | Misoprostol (Cytotec®) |
|---|---|---|
| Active Ingredient | Prostaglandin E2 analog | Prostaglandin E1 analog |
| Administration | Vaginal insert or gel placed near the cervix | Tablet placed vaginally or given orally |
| FDA Approval Status | FDA-approved for cervical ripening | Off-label use for cervical ripening |
| Removability | Easily and quickly removed via a retrieval string | Dissolves, cannot be easily retrieved |
| Cost | More expensive per dose | Significantly less expensive |
| Speed of Action | Slower, more gradual release | Can be faster-acting, depending on dose |
| Uterine Hyperstimulation | Associated with a risk, but manageable due to easy removal | Risk varies by dose; less control over uterine activity once administered |
| Storage | Requires refrigeration until use | Stable at room temperature |
Potential Side Effects and Risks
While generally safe and effective under medical supervision, cervical ripening medications carry potential side effects and risks. Common side effects often include:
- Nausea and vomiting
- Diarrhea
- Fever
- Abdominal cramps or pain
- Backache
More serious, though less common, risks include:
- Uterine Hyperstimulation: Contractions that are too frequent, too strong, or last too long can be dangerous for both mother and baby. Close monitoring is crucial to manage this risk.
- Fetal Distress: Changes in the baby's heart rate can indicate distress, a potential complication of uterine hyperstimulation.
- Uterine Rupture: For individuals with a prior cesarean section or uterine surgery, misoprostol is typically contraindicated due to an increased risk of uterine rupture.
- Infection: In rare cases, infection can occur following administration.
Conclusion
The "pill they put in your cervix" refers to prostaglandin medications like dinoprostone (e.g., Cervidil) or misoprostol (e.g., Cytotec) used for cervical ripening. This process, a common part of induced labor, helps soften and prepare an unripe cervix for delivery. The choice of medication, administration route, and dosage is carefully determined by a healthcare provider based on the patient's individual medical history and pregnancy factors. Because of the potential risks, administration is always conducted in a monitored hospital setting to ensure the safety of both mother and baby. For more information on labor induction, consult authoritative medical resources like the American College of Obstetricians and Gynecologists (ACOG) guidelines.
