Preterm birth

Preterm Birth 

Patient Information

Obstetrics

Introduction

The purpose of this leaflet is to provide information to women who have been identified as being at higher risk of having a preterm (premature) birth. We hope this leaflet will be helpful in understanding the risk factors and how the Preterm Birth Team will support you during pregnancy to try and reduce the risk of preterm birth. If you have any questions or concerns, please speak to the midwife or doctor caring for you. 

What is a preterm birth?

We normally expect babies to be born between 37- 42 weeks of pregnancy. When babies are born before 37 weeks, then it is known as a preterm (premature) birth. About 8 out of 100 babies will be born prematurely before 37 weeks. 

Reasons for referral

We offer referrals to the Preterm Birth Clinic for the following reasons: 

• You went into labour naturally and had your baby between 24+0 and 33+6 weeks gestation in a previous pregnancy 
• You went into labour and had a late miscarriage between 16+0 and 23+6 weeks gestation 
• Your waters broke between 16+0 and 33+6 weeks in a previous pregnancy (called preterm prelabour rupture of membranes [PPROM]). 
• You have had previous surgery on your cervix such as a LLETZ (large loop excision of the transformation zone), or cone biopsy to remove abnormal cells in the cervix 
• You have had a previous Caesarean section in labour when you were fully dilated (your cervix was fully open) 
• You had a cervical cerclage (stitch) in a previous pregnancy 
• Previous trachelectomy for treatment of cervical cancer 
• You have a variation in the size and shape of your uterus, e.g. bicornuate, unicornuate uterus, uterine septum
• You have adhesions (scar tissue) in your uterus, sometimes known as Asherman’s syndrome 

When and where will you be offered an appointment

The Preterm Birth Clinic is held at Thomas Linacre Centre on Friday mornings. Your referral will be reviewed by the Preterm Birth Team, and you may be offered an appointment between 12 to 22 weeks gestation, depending on your individual circumstances. You will be sent a letter for your appointment by post after your first scan at around 12 to 13 weeks, or we will contact you sooner if you need an appointment before this time. The preterm birth midwife may contact you to discuss the referral if the team needs more information, or if you need a different plan of care. 

What to expect at the appointment

You will meet a member of the Preterm Birth Team. They will ask questions about your previous pregnancies and medical history to determine your risk of preterm birth. You may be offered a transvaginal scan (an internal scan where a probe is inserted gently into your vagina) to check the length of your cervix (neck of the womb), so as to assess your risk more accurately. This scan would be offered during the appointment. You may only need one cervical length scan, or you may need the scan repeated every 2–4 weeks between 16 and 24 weeks, depending on your specific needs. We will discuss this with you at your appointment. 

During the appointment, you may also be offered a vaginal swab test and urine test to rule out any infections, which can increase your risk of preterm birth. Please contact us in advance if you have any concerns, or if you are anxious about having a transvaginal scan. See below for a picture of the cervical scan procedure.

Please note: It is important that you empty your bladder before the scan, as this enables us to look at the cervix more accurately.

Management for women at risk of preterm birth

Most women who attend the clinic will not require any treatment or further management. We monitor the length of the cervix until 24 weeks of pregnancy, and if the cervix is a normal length (above 2.5cm and closed), you can continue your pregnancy care with your midwife (and your obstetrician if appropriate). Some women may have risk factors that mean we offer treatment prophylactically (preventively) during pregnancy. 

These treatments may include:                                                                                                                           

Progesterone

This is a hormone that plays a role in maintaining pregnancy. Progesterone is a pessary that is given vaginally. If we think you need to start taking progesterone, we would usually start the treatment between 16-24 weeks of pregnancy and continue until at least 34 weeks. It will be stopped if your membranes rupture, or if you have significant bleeding at any point during the pregnancy. There are no known serious side-effects to the mother when using progesterone; at the present point in time, no adverse effects are known with regard to children born to women who took progesterone when pregnant

Cervical cerclage                                                                                                                   

This is sometimes referred to as a cervical stitch or suture. A stitch is placed around the cervix and tied, in order to prevent the cervix opening too early during the pregnancy. This is most commonly done through the vagina (transvaginal), and is done under spinal anaesthetic, where you will be made numb from the waist down. It is then removed vaginally at 36–37 weeks, unless you go into labour, or your waters break before this time. A cervical cerclage can be placed at the beginning of the second trimester (around 12-14 weeks), based on the previous pregnancy history (history-indicated stitch). If you do need a cervical cerclage, we can discuss this with you in more detail at the time. The complications of cerclage include possible complications during the operation, such as bleeding, injury to the cervix, rupture of your bag of waters (which are rare, less than 1%), and failure of the suture to work. If you have the suture, and then your membranes rupture, we will need to remove the stitch due to increased risk of infection.

You may need to be referred to another, more specialist hospital for Shirodkar suture (high vaginal) or transabdominal cerclage (TAC) if we feel this is more appropriate for you. We can discuss this with you in more depth at the time.

What treatment options would be offered to me if my cervix is short (less than 2.5cm).

For those women who are found to have a short cervix, there are several management options we may offer, so as to try and reduce the risk of preterm labour and birth. If the length of the cervix is below 2.5cm before 24 weeks, you would be offered the following options:

A) Do nothing (Expectant management)

B) Progesterone 

Progesterone supplementation, as discussed above, appears to reduce the rate of spontaneous singleton preterm birth in women who have had a previous spontaneous preterm singleton birth, and in women with a short cervix, on ultrasound examination in the current pregnancy.

C) Cervical Cerclage

Cervical cerclage, as discussed above, will be offered to you in response to the cervix starting to shorten (an ultrasound indicated stitch). You will be offered a stitch into your cervix if it measures less than 2.5cm but is not fully open. This is done before 24 weeks, and has been shown to reduce the risk of preterm delivery before 32 weeks by 25%.

Is progesterone better than stitch?

There are no studies comparing progesterone with stitch on the cervix; however, a recent study has done an indirect comparison of the two. The key finding of this study is that vaginal progesterone and cervical cerclage have similar efficacy (or are no different) for the reduction of risk of preterm birth, and for the adverse outcomes for the baby in women with a short cervix and a history of preterm birth.

Supporting you in preterm labour

Being in preterm labour means that you will start feeling regular contractions (which may be painful) before you have completed 37 weeks of pregnancy. The contractions will be strong enough to make the cervix dilate. If you are assessed in hospital with signs of preterm labour, you can expect the following:

• History taken about any symptoms you may be experiencing. 
• Observations to be undertaken
• Urine tested
• Assessment of fetal heartbeat
• Review by a doctor
• They may offer you an examination to look at the cervix. This is usually a speculum examination (like a cervical smear test), to find out if the cervix has started to open, or if there is any fluid leaking or any bleeding.
• They may offer a Fetal Fibronectin Test to help assess your chances of preterm labour

Some signs and symptoms of preterm labour

• Backache (intermittent or continuous)
• Cramps like strong period pains (usually more painful than Braxton-Hicks 'practice' contractions, although these can also be painful in late pregnancy)
• Frequent need to urinate
• Feeling of pressure in your pelvis
• Feeling sick (nausea), being sick (vomiting) or having diarrhoea
• A 'show' when the mucous plug in the cervix comes away
• Your waters breaking. Sometimes you may feel a soft, popping sensation. There may be a slow trickle or a gush of clear or pinkish fluid from your vagina.

Preterm prelabour rupture of membranes (PPROM)

This is when your waters break before your labour starts and before you reach 37 weeks gestation. If this happens, it can sometimes trigger early labour, but not always. 

It is diagnosed when pooling of amniotic fluid is seen either on a pad or by speculum examination. If you are unsure that your waters have broken and we cannot see any fluid pooling during the speculum examination, we can offer a swab test. This is a swab test taken during the speculum examination to check for amniotic fluid. The results take 5-10 minutes. 

If your waters have broken, then we would advise that you are admitted to our antenatal ward for observation. This is to observe for signs of labour or infection, and to prepare for possible early birth of your baby. If you think you are in preterm labour or that your waters have broken, please contact the hospital.

Contact numbers

• Less than 16 weeks pregnant - Contact the Early Pregnancy Assessment Unit on

  01942 364857 or Swinley Ward 01942 822568 (or attend the Emergency Department if 

  urgent). 

• Over 16 weeks - Telephone Maternity Triage on 01942 778628

Acknowledgements

Created with input from East and North Hertfordshire NHS Trust 

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