It’s common for the cervix to remain closed well into the third trimester of pregnancy. For most women, the cervix begins to soften, shorten, and dilate in preparation for delivery around weeks 37-40. However, every woman’s body progresses differently. Here’s an overview of why your cervix may still be closed, even late in pregnancy.
What is the cervix?
The cervix is the lower part of the uterus that connects to the vagina. During pregnancy, the cervix serves as a barrier and helps keep the fetus safely inside the uterus.
Here are some key facts about the cervix:
- It’s normally about 2-3 cm long in non-pregnant women
- The cervical canal remains closed and rigid in early pregnancy
- As delivery approaches, the cervix starts to thin out (effacement) and open up (dilation)
- In the last weeks of pregnancy, the cervix prepares for labor by softening and dilating to 10 cm
Why might the cervix remain closed in late pregnancy?
There are several common reasons why the cervix may continue to be closed and firm, even after 37 weeks:
It’s your first pregnancy
For first-time moms, the cervix often doesn’t start dilating and effacing until right around the due date or later. In women who’ve had babies before, the cervix may begin dilating weeks before the due date.
Your baby is in a posterior position
If the back of the baby’s head is against the cervix (known as a posterior position), it can prevent the cervix from opening as quickly. The baby’s head puts added pressure on the cervix.
You’re not having strong or frequent contractions
Regular contractions in late pregnancy help gradually soften and dilate the cervix over time. If you’re not yet having many intense or frequent contractions, that could explain why your cervix is still closed.
Scar tissue on the cervix
Previous injury or surgery involving the cervix can sometimes lead to scar tissue. This scar tissue makes the cervix less elastic and flexible, potentially delaying dilation.
Medical conditions
Some medical conditions are linked to delayed cervical dilation, including:
- Diabetes
- High blood pressure
- Obesity
Problems with the placenta, like placenta previa, may also affect cervical changes.
How can doctors assess the cervix?
There are a few methods doctors use to check cervical changes:
Cervical exam
During a vaginal exam, the doctor manually feels the cervix to check its firmness, position, dilation, and effacement. Exams may start around 36 weeks.
Ultrasound
Transvaginal ultrasounds can provide precise measurements of cervical length and funneling (internal dilation).
Fetal fibronectin test
This test detects fetal fibronectin, a protein that indicates the cervix is preparing for labor. It’s typically done around weeks 24-34.
| Test | What it measures |
|---|---|
| Cervical exam | Dilation, effacement, position |
| Ultrasound | Cervical length, funneling |
| Fetal fibronectin | Cervical changes at cellular level |
What if my cervix is still closed at 40 weeks?
It’s very common for first-time mothers to reach 40 weeks with a closed, thick cervix. However, if you go past your due date, your doctor may start talking about induction to stimulate labor.
If you have no medical or obstetric complications, it’s often fine to wait a while longer for labor to start naturally. Some options may include:
- More monitoring – NSTs and biophysical profiles to check on the baby
- Membrane sweep – Separating the amniotic sac from the cervix
- Induction – Using medications or other methods to start labor
Your doctor can discuss the risks and benefits of waiting versus inducing labor when your cervix remains unchanged later in pregnancy.
Are there ways to help ripen the cervix?
If your due date is approaching, there are some natural techniques that may help encourage cervical changes – although their effectiveness varies:
Walking and exercise
Being active can promote contractions and ease the baby’s descent against the cervix.
Sexual intercourse
Prostaglandins in semen may help soften and dilate the cervix.
Nipple stimulation
Can trigger uterine contractions and the release of oxytocin, a key labor hormone.
Using a birth ball
Sitting and gently bouncing on a birth ball can encourage the baby into the optimal position and put pressure on the cervix.
Acupuncture
May stimulate contractions and promote cervical changes, when performed in the weeks before due date.
When to contact your healthcare provider
Call your doctor or midwife if you have any of the following:
- Signs of early labor (contractions, bloody show, water breaking)
- Change in vaginal discharge or bleeding
- Loss of fluid
- Decreased fetal movement
- Menstrual-like cramping
- Pelvic pressure
- Backache
Even if your cervix is still closed, these symptoms may indicate it’s starting to undergo changes or you could have an infection like bacterial vaginosis.
When to consider induction
Your doctor will likely recommend inducing labor if:
- You’re more than 1-2 weeks past your due date
- There’s an obstetric emergency putting you or baby at risk
- Tests show the placenta is no longer functioning properly
- Your water breaks but labor doesn’t start naturally
- You develop preeclampsia or gestational diabetes
Waiting too long after your due date increases the risk of complications. However, your doctor will discuss whether it’s safe to allow more time for natural labor to begin.
Conclusion
It’s very normal for the cervix to stay closed and firm until the final weeks of pregnancy, especially in first pregnancies. However, your doctor will keep an eye on the cervix throughout the third trimester and can perform exams to determine if induction is needed.
Try not to worry too much if you haven’t had cervical changes by weeks 37-38. You may just need those last couple weeks of pregnancy for your cervix to ripen and activate labor. Talk to your healthcare provider about any concerns.