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Short cervix in pregnancy
7-minute read
Key facts
- The cervix is part of the female reproductive system and is found at the lower part of the uterus connecting to the vagina.
- A short cervix during pregnancy increases the chance of having a preterm (early) birth.
- You are more likely to have a short cervix if you have a history of preterm birth or have had a procedure where a part of your cervix was removed.
- A short cervix can be diagnosed on a routine pregnancy ultrasound.
- A short cervix can be managed during pregnancy with progesterone medicine or a procedure called cervical cerclage.
What is the cervix?
The cervix is part of the female reproductive system. It is a channel that connects your uterus with your vagina.
The cervix is usually about 3cm long and has an internal opening (into the uterus) and external opening (into the vagina).
The cervix is responsible for keeping the uterus closed during pregnancy. During labour, the cervix relaxes and slowly opens so that your baby can be born.
What does it mean to have a short cervix during pregnancy?
Your cervix is considered to be short if it is less than 25mm (2.5cm) long before 24 weeks of pregnancy. The shorter your cervix, the higher the risk of your baby being born early (before 37 weeks of pregnancy).
Sometimes, a short cervix may be a sign that your cervix is too weak to keep your uterus closed until your baby is ready to be born. This is called 'cervical insufficiency'.
What are the symptoms of a short cervix?
A short cervix often doesn't cause any symptoms, and is only discovered on a routine pregnancy ultrasound.
If you have cervical insufficiency, you might have:
- a feeling of pressure in your lower tummy
- back pain
- spotting or light bleeding from your vagina
- more discharge than usual from your vagina
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What causes a short cervix?
It's not always clear what causes someone to have a short cervix, but there are some known factors that increase your risk.
Your risk of having a short cervix is higher if you have had a previous preterm birth.
You are also at a higher risk if you have had a procedure where a small part of your cervix was removed — such as a cone biopsy or loop excision. These procedures are used treat abnormal cells on your cervix.
When should I see my doctor or midwife?
Make sure to see your doctor or midwife for routine pregnancy care. They will advise you when you should have an ultrasound to check your cervix.
See your doctor or midwife as soon as possible if you have symptoms of cervical insufficiency.
You should also see your doctor or midwife urgently if you had a cervical cerclage (stitch) placed and have symptoms such as:
- fever
- abdominal pain
- signs of labour
- vaginal bleeding
- your waters breaking
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How is a short cervix diagnosed?
A short cervix can be diagnosed using ultrasound. The length of your cervix will be measured on your routine mid-pregnancy ultrasound. This scan is done over the skin of your tummy.
If your cervix looks shorter than expected, or if the ultrasound technician has difficulty seeing your cervix properly, they may suggest a transvaginal ultrasound. This is an ultrasound performed using a probe inserted into your vagina. A transvaginal ultrasound allows the cervix to be seen better and measured more accurately.
Your doctor may also suggest a transvaginal ultrasound if you are at high risk of having a short cervix.
How is a short cervix treated during pregnancy?
There are different ways to manage a short cervix during pregnancy. The aim of treatment is to lower your risk of preterm (early) birth. Your doctor will discuss treatment options with you, depending on your level of risk.
You may be referred for follow-up ultrasound scans later on in your pregnancy to check if your cervix is getting shorter.
Progesterone
Progesterone can lower the risk of preterm birth. This medicine is given in the form of a small tablet, placed directly into your vagina every day until you reach 36 weeks of pregnancy.
Cervical cerclage
Cervical cerclage is a surgical procedure where a stitch is placed in your cervix to keep it closed.
Your doctor may suggest this treatment if you have a history of premature birth or a pregnancy loss during the second trimester, or if your cervix continues to get shorter despite using progesterone daily. They may also recommend it if your cervix is very short (less than 10mm).
The stitch is removed at about 36 weeks of pregnancy, or earlier if you go into labour.
What are the complications of having a short cervix during pregnancy?
Having a short cervix puts you at higher risk of giving birth early — but keep in mind that most people with a short cervix give birth on time.
Premature birth can lead to health problems in the newborn period and later in life.
Learn more about premature birth.
Can a short cervix in pregnancy be prevented?
It isn't usually possible to prevent having a short cervix, but routine antenatal care can help identify the condition early when it can be treated effectively and minimise the chance of complications.
Resources and support
Visit Miracle Babies Foundation to find out more about having a premature baby.
If you are feeling stressed during pregnancy, visit the Centre of Perinatal Excellence (COPE) for information and support.
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week (including public holidays).
Looking for information for Aboriginal and/or Torres Strait Islander people?
Find an Aboriginal Community Controlled Health Organisation (ACCHO) in your area.
Looking for information for sexually and gender-diverse families?
Read more about pregnancy for sexually and gender-diverse parents.
Speak to a maternal child health nurse
Call Pregnancy, Birth and Baby to speak to a maternal child health nurse on 1800 882 436 or video call. Available 7am to midnight (AET), 7 days a week.