Weak cervix (cervical incompetence): symptoms, causes and treatment

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Signs and symptoms of a weak cervix in pregnancy

Causes of a weak cervix

Monitoring and treatment for a weak cervix

Coping with having a weak cervix

Sometimes the neck of the womb (the cervix) shortens and opens too soon in pregnancy. This can lead to your baby being born prematurely (before 37 weeks). Read about the signs of premature (preterm) labour.

You may hear different names for this problem: weak cervix or weakened cervix, cervical incompetence, and cervical insufficiency. These are just medical terms, but we know that some women and birthing people do not like these terms and prefer to call it ‘preterm cervical shortening’.

“I lost my first baby at 20 weeks due to an ‘incompetent cervix’. Nobody could have predicted this would happen, but I still blamed myself for ‘losing’ my baby. We need to understand that this is a medical condition. Nobody is to blame. Getting a diagnosis is vital, so that you can then get the right treatment to support you through any future pregnancies.”

Susan

Signs and symptoms of a weak cervix in pregnancy

Your cervix can shorten and open without any pain or other symptoms. It is usually only diagnosed when a person has had 1 or more late miscarriages or premature babies, and other causes have been ruled out.  

Some people with preterm cervical shortening may have smelly and/or yellow or green vaginal discharge, bleeding, or a feeling of pressure in the lower tummy area or vagina. Tell your maternity team if you have these or any other symptoms you are worried about.  

Causes of a weak cervix

You may have been born with a cervix that is prone to shortening and opening too soon. This could be because you have a differently-shaped womb (uterus) or because you have a condition affecting collagen production, such as an Ehlers-Danlos syndrome, for example.

Injury to the cervix can weaken it. This is often from a surgical procedure. For example, from treatment for abnormal cells found on cervical screening, such as LLETZ (largo loop excision of the transformation zone) or a cone biopsy.  

Your cervix may have been injured during a previous labour. 

If you had an emergency  c-section when fully dilated, it may have damaged the top of your cervix – particularly if the scar is low on your womb.

Monitoring and treatment for a weak cervix

When you first see a midwife at your booking appointment, they will assess whether you would benefit from extra monitoring. If you have previously had a late miscarriage or given birth before 34 weeks, or are at risk of having a weak cervix, you should be referred to a specialist early in your pregnancy to plan your care.  

If you have had 3 or more preterm births or second trimester losses and are pregnant with 1 baby, you may be offered a cervical stitch based on this. This is usually done as a planned procedure in people without symptoms between 11 and 14 weeks, to give you a better chance of staying pregnant for longer.

You may be offered a vaginal ultrasound scan to measure your cervix, usually between 16 and 24 weeks. This can be helpful for decisions about possible treatment. Having a cervix shorter than 25mm has been linked to increased risk of preterm labour and birth.  

If scans show you have a weak cervix, you may be offered treatment to help you stay pregnant for longer. You may have a choice between cervical stitch or vaginal progesterone. Your midwife or doctor will discuss with you the risks and benefits of treatments. They may recommend one over the other, but your preferences will be important. There is no evidence to show that one of these two treatments is better than the other.  

Read more about making decisions in pregnancy. 

Progesterone

Treatment with vaginal progesterone involves putting a progesterone medication into your vagina, usually up until 34 weeks of pregnancy. The progesterone pessary is shaped like a small tampon and most people find it easy to put in.    

Progesterone is a hormone that is important in supporting pregnancy in several ways, including helping keep the womb relaxed and lowering the risk of early labour. However, it does not always work.  

Cervical stitch (cerclage)

Putting a stitch into your cervix (a cervical stitch or cerclage) can help keep it closed and reduce your risk of having a miscarriage or preterm birth, though it does not always work.  

Vaginal cervical stitch

Most people who have a cervical stitch have it put in through the vagina. It’s usually done as a planned procedure between 11 and 24 weeks of pregnancy. It’s done in an operating theatre. You may have a spinal anaesthetic, where you will stay awake but be numb from the waist down, or a general anaesthetic where you are asleep.

If you have a stitch and are planning to have a vaginal birth, it will need to be taken out before you have your baby. This would normally be at around 36 to 37 weeks, unless you go into labour sooner. If you are having a planned caesarean the stitch can be taken out then.

Transabdominal cervical stitch

If you have had a cervical stitch before and it hasn’t worked, or if you have had extensive surgery on your cervix, you may be offered a cervical stitch that is put in through your abdomen (tummy). It may be done through a cut in your abdomen or via keyhole surgery.  

This type of cervical stitch is not taken out and you would need to have your baby by c-section.

Emergency cervical stitch

If your cervix has started to open, and you are between 16 and 28 weeks pregnant, you may be offered a cervical stitch as an emergency procedure to try to delay your baby’s birth. This is more risky and is less likely to work than the other types of stitch. Your doctor will discuss with you the risks and benefits of this treatment. 

Why might a cervical stitch not be an option?

There may be reasons why a stitch isn’t a good option for you, because it may have risks for you and/or wouldn’t help your baby. These include if:

• you have vaginal bleeding
• you have signs of infection
• your waters have broken
• you're having contractions
• you're pregnant with more than 1 baby.

Also, if your cervix is already too short or too far open, it may not be possible to put a stitch in. 

If scans show you have a short cervix, but you are pregnant with 1 baby and don’t have any other risk factors for preterm birth, a stitch isn’t recommended.

Read more about having a cervical stitch and about treatments to prevent a premature birth.  

Coping with having a weak cervix

It’s normal to feel a mix of emotions, including guilt, fear and sadness, when told you’re at risk of premature birth. Being on high alert for symptoms of preterm labour and needing to attend extra hospital appointments can also cause extra worry.    

Some people say they feel guilty when they go through a late miscarriage or premature birth caused by a weak cervix. Some of the terms used to describe their cervix opening too soon, like ‘incompetent’, can add to the feeling that it is their fault.  

Don’t be afraid to tell your healthcare professional how you feel. They won’t judge you and are there to support you.  

You can also speak to one of our midwives for free by calling our pregnancy line on 0800 014 7800 (Monday to Friday, 9am to 5pm), or book a call with our Black and Black-Mixed Heritage Helpline midwives or email us at [email protected].  

Read about mental health in pregnancy and sources of support.