Preterm birth

This information has been created for parents and families experiencing threatened preterm labour, on behalf of the Northwest Neonatal Operational Delivery Network and Cheshire & Merseyside Local Maternity and Neonatal System.

What is preterm labour?

Preterm labour is when labout starts before 37+0 weeks of pregnancy. A normal pregnancy lasts between 37-42 weeks, dated by the scan undertaken in early pregnancy (around 10-14 weeks from your last period). In the UK, 6-8% of babies are born preterm. This can be due to medical reasons (early delivery recommended by your doctor due to concerns about you or your baby) or more commonly, can occur on their own. In cases of spontaneous preterm labour, this can sometimes occur after your waters break early (premature prelabour rupture of membranes or PPROM).

Extremely preterm birth is when babies are born before 27 weeks of pregnancy.
Very preterm is where babies are born between 27+0 and 31+6 weeks of pregnancy.
Moderate preterm is birth between 32+0 and 34+6 weeks of pregnancy.
Late preterm is birth between 35+0 and 36+6 weeks of pregnancy.

Not all women who are in threatened preterm labour will birth their baby early, many will go on to give birth much later at term, or after 37 weeks of pregnancy.

In those who do go on to birth early, especially before 27 weeks of pregnancy, the baby is at higher risk of problems related to underdevelopment or immaturity of certain organ systems, particularly the lungs, brain, and bowel. These problems include difficulty with breathing, staying warm, feeding, as well as injury to the eyes and nervous system.

This is why it is so important to attend hospital if you have any symptoms described below, so we can assess you and plan your care to make sure your baby is given the best possible start should they be born early. More written information about these treatments are available in the NWNODN Preterm Optimisation Passport/Leaflet, which will be given to you if you are admitted to hospital.

What are the risk factors?

It is difficult to predict who will develop preterm labour. Of all preterm labour cases, around one third will have risk factors that could possibly increase the chances of it happening. There are certain obstetric conditions and other factors that are known to increase a woman’s risk.

These risk factors divided into ‘high’ and ‘intermediate or moderate’ risk factors:

High:

Previous early water’s breaking before 34 weeks of pregnancy
A different shaped womb (sometimes called bicornuate or septate)
Previous treatment for cervical cancer
Previous use of a cervical cerclage in pregnancy
Ashermann’s syndrome (scar tissue within the womb)
Multiple pregnancy (twins or triplets)

Intermediate:

Previous delivery by caesarean birth at full dilatation (10cm)
Previous surgery to the neck of the womb (cervix)

The strongest risk factor for preterm birth is a previous preterm birth, although most women who have had a previous preterm birth will have a term pregnancy in future.

If you have any of these risk factors, you will be referred to your local hospital’s preterm birth clinic or dedicated multiple pregnancy clinic and be seen around 16-20 weeks.

Other things that can increase your risk of preterm labour are:

Smoking
Short time between births (less than 12 – 18 months)
Recreational drug use

What are the causes of preterm labour?

Preterm labour is a complex condition, often with no obvious cause, but there are several known problems in pregnancy which can lead to preterm labour, such as:

Bleeding from the womb in the second or third trimester
Stretching of the uterus due to multiple pregnancy or more than normal fluid around baby
Bacteria or inflammation – such as symptomatic bacteriuria or bacterial vaginosis
Severe physical or psychological stress

What are the symptoms and when should I seek medical advice?

The signs and symptoms of preterm labour are similar to the signs at the end of pregnancy but can sometimes be more subtle and if you have any concerns then it’s very important that you contact Maternity Triage to be checked over.

Signs and symptoms to be aware of:

A change in the type or amount of vaginal discharge you make (watery, mucus like, bloody)
Any vaginal bleeding
Lower back ache
A feeling of pressure down below
Period-like cramping pain
Regular or occasional tightening of the womb, which may be painless.
A gush of fluid or sensation of a pop (which could mean your waters have broken)

These symptoms may not be anything to be concerned about, but it is very important to seek medical attention so we can assess you and your baby’s wellbeing and rule out whether there is a possibility that you could be going into preterm labour.

What will happen when I attend the hospital?

You will first be triaged by a midwife in maternity triage, who will ask you about your symptoms, take your observations (heart rate, blood pressure, temperature) and assess the wellbeing of your baby by listening in and monitoring your baby’s heart rate.

You will be reviewed by an advanced nurse practitioner or a doctor, which will involve performing an examination of your abdomen and a speculum examination.

It may be recommended to have an internal scan to measure the length of the neck of the womb (the cervix) and have a small swab taken to identify and measure the amount of a substance called fetal fibronectin – which is released when the membranes around the baby start to change prior to labour.

Your overall risk of preterm labour is assessed, and you and your baby’s care will be planned depending on this.

How is preterm labour treated?

You will be admitted to hospital for close observation of you and your baby. Evidence suggests that the highest chance of preterm delivery occurs in the first 7 days after diagnosis, particularly if your waters have also broken. It is likely you will have a cannula sited (known as a ‘drip’, a small plastic tube to allow intravenous medications to be given) and routine blood tests taken.

A medicine called Nifedipine can be given to slow down any contractions. The aim of this is to delay labour long enough so that a course of steroids, which is usually 2 injections (1 at diagnosis then the second 24 hours later), is completed.

Steroids are given to boost the development of the baby’s lungs and the production of a substance called surfactant, which helps provide oxygen to the body. Steroids also help to reduce the risk of bleeding into the brain (called intraventricular haemorrhage) and other complications which affect the bowel and circulatory system.

Delaying labour may also be necessary depending on the unit you are in and the stage of your pregnancy, as you may need to be transferred to another unit with an appropriate level neonatal unit to ensure the best care for your baby if they are to be born early.

In some cases where preterm labour occurs, a medication called Magnesium Sulphate is given through a drip in the arm to help protect the baby’s brain. Evidence has shown that is reduces the risk of cerebral palsy in babies born early.

If you are in active preterm labour antibiotics will be given through a drip to help prevent any infections, as preterm babies are more prone to infections.

The obstetric doctors will also inform the neonatal team to have a joint discussion between you and the team to discuss treatment options and answer any questions you may have about what happens should your baby be born early.

What can I do to help prevent preterm labour?

One of the most important things a pregnant woman can do is to stop harmful habits, such as smoking and the use of recreational drugs. We will monitor your carbon monoxide levels throughout pregnancy, and if you smoke tobacco, we will refer you to the smoke free pregnancy team to support you to stop smoking in pregnancy.

If you are concerned that you are experiencing any of the signs or symptoms described above, then it is very important that you do not delay contacting your local maternity triage unit to be assessed. The safety of you and your baby are our utmost priority and we understand that it can be a frightening time, so advise you to come in and soon as you can rather than be worried at home.

What other information or support is there for me?

We understand that some of this information may be upsetting or distressing, if you feel as though you would like to discuss this more at length or have more support then always contact your named midwife or ask to have a chat with a member of the Obstetric team (doctors who specialise in the care of pregnant women and unborn babies).