When you’re pregnant, you learn all kinds of things about your anatomy that you may not have known before. And sometimes, you learn things that require extra care during pregnancy.

That’s the case if you have a short cervix.

The cervix is the opening at the bottom of the uterus that connects the uterus and the vagina. When you’re not pregnant, it’s generally pretty short — about 25 millimeters (mm) on average — and closed.

During pregnancy, the cervix gets longer, putting a more protective distance between your baby and the outside of your body.

In one study involving 930 pregnant women, the average cervical length at 8 weeks gestation was nearly 41 mm.

But as pregnancy progresses, the cervix does start to shorten again in preparation for delivery. In fact, it’s the shortening, opening, thinning, and softening of the cervix that allows for baby to travel through the birth canal and be born.

Makes sense, right? But if you have a shorter cervix earlier in your pregnancy, the natural shortening that happens as the weeks pass by may make it too short, too early — resulting in premature labor and birth. It can even cause miscarriage (pregnancy loss before 20 weeks gestation).

In an older but foundational study, researchers found that women whose cervix measured 15 mm or less at 23 weeks gestation made up the majority of preterm births occurring at 32 weeks or earlier.

The conclusion? Cervix length is a pretty good predictor of preterm birth.

Since the goal is to keep your “bun in the oven” as long as possible, it’s important to get a short cervix diagnosed and treated to prevent cervical insufficiency — the early softening and opening (dilation, in pregnancy speak) of your cervix.

The main cause of a short cervix is cervical insufficiency, also called incompetent cervix. This can be caused by previous:

  • trauma to the cervix area (such as during a procedure like a dilation and curettage — but note, this is rare)
  • damage to the cervix during a difficult birth
  • exposure to the hormonal drug diethylstilbestrol (that is, if your mom took it while she was pregnant with you)
  • cervical rupture

Cervical insufficiency can also be congenital, or something you’re born with due to the shape of the uterus.

A short cervix in and of itself doesn’t cause symptoms. However, a couple of signs that you may have a short cervix include:

  • previous second-trimester miscarriage(s) (short cervix is a leading cause of this)
  • previous premature birth due to going into labor spontaneously before 37 weeks

There are other causes for these things — and of course these signs won’t even exist if it’s your first pregnancy — so you (and your doctor) may have no reason to think that you have a short cervix.

However, if you do have these signs, your OB may bring up measuring your cervix as part of current or future prenatal monitoring.

Additionally, you may have some symptoms during pregnancy if you have cervical insufficiency.

During your second trimester, tell your doctor if you have any of the following symptoms of incompetent cervix:

These symptoms may also prompt your doctor to check for a short cervix.

If you’re considered at higher risk for a short cervix — due to previous preterm labor or birth, history of miscarriage, or family members with a short cervix — your doctor will do a transvaginal ultrasound to measure your cervix.

This type of ultrasound is considered the gold standard for measuring the cervix.

If you’ve had previous losses or preterm deliveries, your doctor may make this measurement toward the start of your second trimester, or around 12 to 14 weeks.

If your cervix measures less than 25 mm at this stage, your doctor will diagnose you with a short cervix.

This isn’t part of standard prenatal visits if you haven’t had previous warning signs. But remember that you can always ask your doctor for a cervix measurement, even if you’re not considered at risk.

Your OB is there to help you throughout your pregnancy and put your mind at ease.

The good news for you and baby is that — once your doctor knows about your short cervix — there are treatments that can help delay delivery as long as possible.

Cervical cerclage

This is basically a strong stitch that closes the cervix.

If you’ve had issues with a short cervix in the past, if your cervix measures less than 25 mm, or if you have cervical incompetence, your doctor may recommend getting a cerclage early in the second trimester to prevent miscarriage and keep baby nice and secure.

Rest assured, a standard cervical cerclage isn’t forever. Your doctor will remove the stitch once it’s safe for you to deliver — anywhere from 36 to 38 weeks.

Remember, 37 weeks is considered a term pregnancy, so this is good news!


If you’re considered high risk, your doctor may prescribe progesterone as an injection or vaginal suppository (no, it’s not fun — but it’s worth it, as we’ll explain).

In 2 clinical trials referenced in one study, progesterone proved helpful in reducing preterm birth. In fact, for the women who had previously given birth preterm, progesterone reduced the reoccurrence of this in a subsequent pregnancy by as much as half across the group.

So while shots can sting and suppositories can be messy, progesterone can lower your risk of early, spontaneous delivery if you have a short cervix — and therefore keep baby inside the womb longer.

Arabin pessary

An Arabin pessary is considered a newer alternative to cerclage and progesterone. It’s a small ring designed to wrap around the cervix and close it — no surgery required.

One study that compared cervical cerclage and pessary found that a cervical pessary may be the better option if you have funneling.

You can have a short cervix without funneling, but funneling means it starts to take on a V- or U-shape. But researchers did say that more research is needed.

Ask your doctor more about this option if you have a short cervix.

Bed rest

Sometimes, a doctor may recommend bed rest (or pelvic rest) and continued monitoring for a short cervix. This can mean anything from no sex or strenuous activity to full-on, only-get-up-to-pee-and-eat bed rest.

However, it’s important to note that strict bed rest has not been proven to prevent preterm labor.

Load up your tablet with novels and your movie library with upbeat films to stream. Hang in there. You’ve got this.

A short cervix is something you may have without knowing it, and it generally won’t be an issue outside of pregnancy. But if you’re pregnant, getting a short cervix diagnosed is crucial so you can get the right treatment.

As always, talk to your doctor openly about your concerns. Keep up with your prenatal appointments, and pay attention to any new symptoms.

Fortunately, research has advanced and treatments for a short cervix are very effective.