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Multiple pregnancy and screening for preterm birth

What is preterm birth?

Women and pregnant people with a twin or triplet pregnancy are at an increased risk of giving birth early (before 37 weeks of pregnancy). This is called premature birth.

  • Around 60 in 100 twin pregnancies result in birth before 37 weeks
  • Around 75 in 100 triplet pregnancies result in birth before 35 weeks

Being pregnant with more than one baby increases the risk of some conditions, either in you (e.g. high blood pressure, pre-eclampsia) or your babies (e.g. growth problems), which may lead to early birth being recommended (this is called iatrogenic preterm birth). However, sometimes labour can start early on its own (spontaneous preterm birth) and it is not always clear why this occurs. Even if the cause is known, it is not always possible or safe to stop the babies from being born early.

The health risks for babies born early depend on how early they arrive. Babies born closer to 37 weeks usually do well and may only need minimal extra care. However, babies born much earlier are more likely to need specialist medical support and have a higher chance of long-term health problems.

Reducing preterm birth

The National Institute for Health and Care Excellence (NICE, 2024) guideline for twin and triplet pregnancy recommends offering an internal (transvaginal) scan to check the length of the cervix (the neck of the womb). This scan helps assess the risk of preterm birth, as a shorter cervix can mean a higher chance of going into labour early. In light of this, we suggest having this scan around 20 weeks of pregnancy. However, most women with a shorter cervix will not deliver earlier than expected.

If the cervix measures 25 mm or less, we may recommend starting vaginal progesterone pessaries (small tablets inserted into the vagina, usually once a day), which may reduce the risk of subsequent preterm birth. Progesterone is a natural hormone produced during pregnancy and may help reduce the risk of early birth by keeping the womb relaxed. This treatment usually continues until 34–36 weeks of pregnancy.

You will also be offered follow-up appointments and care through a specialist preterm birth clinic where we can monitor you closely, discuss management options and support you throughout your pregnancy.

Signs and symptoms of preterm labour

If you are concerned that you are experiencing any signs or symptoms of preterm labour, it is very important that you contact us and do not delay attending your local maternity unit to be assessed.

Speak to a midwife if you experience:

  • A change in vaginal discharge (watery, mucus-like, or bloody)
  • Any vaginal bleeding
  • A loss of fluid from the vagina or a popping sensation (which could mean your waters have broken)
  • Period-like cramping pain in your lower tummy or back
  • Regular or occasional tightening of the womb
  • Lower back pain that is getting worse
  • A feeling of pressure on your vagina

Your safety and the safety of your babies are our utmost priority. We understand this can be a frightening time, so we advise you to come into hospital rather than worry at home. These symptoms may not be anything to be concerned about, but it is important to seek medical attention so that we can assess you and your babies’ wellbeing and rule out preterm labour.

The Maternity Assessment Suite provides 24/7 care from 20 weeks at Chelsea and Westminster Hospital and from 18 weeks at West Middlesex University Hospital. Please call the unit to discuss any concerns and we will advise you if you need to attend.

Chelsea and Westminster
T: 020 3315 6000, option 1

West Middlesex
T: 020 8321 5839

Prior to 20 weeks at Chelsea and Westminster or prior to 18 weeks at West Middlesex: If you have an urgent concern regarding the symptoms above, please contact your midwife, GP or attend your nearest Emergency Department.

Common questions

Can I continue to work during my pregnancy?

Yes. There is no evidence that continuing work increases the risk of preterm birth. Depending on your occupation and individual circumstances, some time off may be appropriate. Please discuss this with your midwife or doctor.

Can I exercise during pregnancy?

In most cases, yes. Gentle to moderate exercise is safe, recommended and beneficial. However, activities that may pose a risk of injury to the abdomen, cause falls or put excessive stress on joints should be avoided.

Can I do anything to prevent preterm birth?

  • Don’t smoke: Smoking increases the risk of preterm birth. Stopping smoking brings benefits for both you and your babies. Support is available through our stopping smoking services.
  • Avoid vaginal douching: This can upset the vagina’s natural balance, increasing the risk of bacterial vaginosis and possibly preterm birth.
  • Prevent infections: Stay well hydrated and reduce the risk of vaginal and urinary infections.

Research

Research into why preterm birth happens is essential to saving lives and preventing future loss. Chelsea and Westminster Hospital and West Middlesex University Hospital are actively involved in studies in this area. You may be invited to take part. A midwife or doctor will discuss suitable studies with you and answer any questions you may have.

Taking part is voluntary, and you do not have to participate if you do not want to. Your support could help improve care and outcomes for other families in the future.

Further information

Contact information

Chelsea and Westminster Hospital

Antenatal Clinic
369 Fulham Road
London
SW10 9NH

T: 020 3315 6000

West Middlesex University Hospital

Queen Mary Maternity Unit
Twickenham Road
Isleworth
Middlesex
TW7 6AF

T: 020 8560 2121