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Cervical Weakness or Insufficiency

The cervix connects the uterus to the vagina.

Usually between two and a half to four centimetres long, it helps block access to the uterus from the vagina.

Every month the cervix will close a little to prepare the uterus for pregnancy. If the egg remains unfertilised, the cervix will then open a little to allow the menstrual blood out.

If you do fall pregnant, the cervix will close, and a mucus blob will form along the length of the cervix to physically and biologically protect your baby during pregnancy.

Throughout the first trimester, the cervix remains largely as it has always been. However, during the second or third trimester, the cervix will shorten as your uterus stretches to accommodate your baby. When the cervix shortens, the mucus blob will thin to ensure your baby stays protected.

A cervical insufficiency occurs when the cervix opens too early

This means the mucus blob is no longer there to protect your baby, which means a premature birth or late miscarriage can occur.

The main issue with a cervical insufficiency is there is often no tell-tale pain or discomfort. Sometimes, the only sign anything may be wrong is the appearance of a larger ‘blob’ of rubbery mucous or a bright trickle of blood. There are other signs, like backache or mild cramps. However, these are also symptoms of many pregnancy and non-pregnancy issues and often cause more emotional stress than anything.

The causes of cervical insufficiency

There are some risk factors we know of. These include

  •       previous cervical surgery
  •       a family history of a similar problem
  •       congenital uterine abnormalities
  •       multiple rounds of IVF
  •       multiple curettes for miscarriage.

It can also simply be a weakened connective tissue with the cervix. Unfortunately, many times there are no apparent risk factors we can identify.

Diagnosis and assessment of cervical insufficiency

The best way to test for a cervical insufficiency, and assess whether you have cause for any concern, is by doing a trans-vaginal ultrasound during the second trimester. 

This thin wand helps provide a complete picture of the vagina and the integrity of the cervix. And helps Guy determine whether you need any extra care, and what management options, if any, you may need.

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These management options can include hormonal and non-hormonal medications. In some instances, if there is a real risk of insufficiency, there may be a need for a physical intervention. In these rare cases, a simple surgical placement of a strong circumferential band (cervical suture) helps the cervix remain closed until your baby is strong enough to either handle a slightly premature birth (or may go full term). 

Guy will take you through the chances of you having this condition and, if so, what treatments are available to you. Our focus is, and will remain, the health of you and your baby throughout your pregnancy.


Cervical weakness is a condition that affects about 1% of pregnancies. The cervix is the lower part of the uterus and usually closed – like a long, firm tube. This closure is aided by mucus which softens during ovulation to allow sperm to travel through the cervix. When you fall pregnant, the cervix is closed and firm. As your pregnancy progresses, the cervix begins to widen and thin out – getting ready for when you deliver. Cervical weakness happens when the cervix begins to widen and thin out too early, causing it to open early, often resulting in a premature birth.

Left untreated, and unmonitored, a weak cervix can be a pregnancy risk and can result in either a premature birth or a loss of the pregnancy.

Many times, even if you have a strong family history of cervical weakness, you won’t know until you fall pregnant. If you have a history of cervical weakness, or premature births, your gynaecologist can monitor it through a transvaginal ultrasound, which checks the length of your cervix, or through a pelvic exam, which checks to see if there is any early signs of the amniotic sac appearing through the cervical opening.

While there are no cures for cervical weakness, you can enjoy a full-term birth with some help from an experienced gynaecologist and obstetrician, like Dr Guy Skinner. These include

  • Progesterone supplements – these have been shown to help the cervix retain its strength and shape through pregnancy in many women
  • Regular ultrasounds – careful and consistent fortnightly monitoring of your cervix, especially through the second trimester, to check the length of the cervix 
  • Stitches – also known as cervical cerclage. If the ultrasound shows Guy your cervix is opening, he may recommend cerclage. This closes the cervix with strong stitches which are removed during the last month of your full term, or during labour.

No. But there is a lot you can do to help you enjoy a healthy, full term pregnancy. 

Visit your obstetrician regularly – so they can monitor your cervix and your baby’s health. 

Let them know anything you notice about the baby. Any symptoms at all. While they may seem trivial, or may not be important, your obstetrician will be able to let you know what they mean, and what, if anything, you need to do about them.

If you’ve experienced a weak cervix, and you want to fall pregnant again, talk to your obstetrician.  They can help you understand the risks, what you might need to do, and help you feel more confident about your pregnancy.