Your guides to the common aches, pains and annoyances of pregnancy!

Premature Labour and Cervical Weakness

Premature labour is when you go into Labour before 37 weeks and a premature baby is one that is delivered before 37 weeks- ie more than 3 weeks early.  It occurs in about 1 in 15 pregnancies and in spite of all recent advances, the rate remains unchanged and may even be rising a little.

The chances of losing a baby are very much related to the degree of prematurity, the size and to a lesser extent, the sex of the baby.  At 32 weeks, (8 week premature), 98 % of babies are expected to survive.  At 23 weeks only 10% are expected to survive and many may have some form of disability.  For the record, premature girls often do better than boys, especially Afro-Caribbean girls.

Causes of Premature Labour and What can be Done?

There are many different causes of prematurity and sometimes the cause is never discovered.

  • The most common reason is because of spontaneous early labour, particularly if your waters have broken prematurely.  It’s thought that infection may play a significant role here but nobody is sure if it is an infection that causes the membranes to break or if an infection occurs after they have ruptured.
  • Other factors that increase the chances of delivering early are recurrent bleeding, physical trauma (eg. a car crash), multiple pregnancies (eg. twins or triplets), congenital abnormalities of the womb, such as abnormal shaped uterus and smoking.
  • Another big factor that increases your chance of a premature labour is having a history of a previous early delivery- this will double your risk.  Two previous premature labours will treble or quadruple your risk.
  • “Cervical Incompetence” or “Cervical Weakness” is another important cause of premature labour which is potentially treatable.  Cervical Weakness may be congenital, (ie you are born with it), or it may occur because of previous surgeries to the cervix such as repeated late abortions or repeated treatments for pre-cancerous cells (eg. loop diathermy). Sometimes having recurrent abnormal smears may increase your chance of delivering early.

Unfortunately, the diagnosis of cervical weakness is not precise and is often sadly only diagnosed after a late miscarriage or very early delivery.

Cervical Cerclage is a treatment that can be effective if the cervix is thought to be weak and if there is a significant past history of previous problems of early labours or late miscarriages.  It involves the application of  a non-absorbable tape around the cervix to strengthen it and to preserve the important mucus plug.  This procedure is often referred to as a “Stitch”.

There are 3 types of stitches, two of which are done through the vagina.  One is very conservative and can be removed without anaesthetic and one a bit more invasive and needs a spinal anaesthetic to be removed.  There is a third type of abdominal suture which is rarely used and involves major open surgery.

A stitch is usually inserted as a day case procedure under a spinal anaesthetic anytime after 14 weeks (after a 12 week scan).  Sometimes the stitch is put in on the basis of past events, sometimes it may be recommended if a careful ultrasound after 14 weeks shows that the cervix is shortening to a significant degree.  Women who are thought to be at extra risk of preterm delivery usually have their cervix measured after 14 weeks and if the cervix shortens significantly, below 25 mm, then a stitch may be recommended.

Occasionally a suture can be inserted after 20 weeks if the cervix starts to open and there is an extremely high risk of imminent delivery.  This is called a rescue stitch.  In these cases steroids may be given to the mother to help mature the baby’s lungs as the risk of pre term labour may be extremely high.

It is not routinely done for multiple pregnancies or after one treatment of pre-cancer.  Even if your cervix is shorter than 25mm it is unusual for a stitch to be inserted unless you have other significant risk factors.

Once the stitch is in place it does give rise to a little extra discharge.  It is usually perfectly safe to behave normally, this includes having vaginal sex if you want to.   Your Midwife or Doctor will advise you on this subject if you have concerns.  There is no evidence that bed rest has any particular part to play in the prevention of prematurity.

The stitch is normally removed between 36 and 38 weeks of pregnancy and is generally performed without a general anaesthetic.  It is often not more disruptive than a normal speculum examination.  If you are having an elective Caesarean Section it can usually be removed during this operation.  However, if go you into pre-term labour or rupture your membranes before 36 weeks it is advisable to have it removed to prevent damage to the cervix or infection.

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