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Threatened preterm labour

Preterm labour

Preterm labour is the onset of labour between 24 and 37 weeks of pregnancy and is characterised by regular and often painful uterine contractions. The cervix (opening to the uterus) can also start to open.

Half of all women who experience symptoms of preterm labour will have no changes to their cervix and the contractions usually stop without treatment.

Women at greater risk of preterm labour

While it is difficult to know who will go into preterm labour, some risk factors include:

  • smoking
  • use of illicit drugs eg. cannabis, sniffing solvents
  • previous preterm birth
  • having babies less than 18 months apart
  • multiple pregnancy—twins, triplets etc
  • some infections e.g. urinary tract infection
  • previous surgery on your cervix
  • bleeding from the uterus during the pregnancy
  • premature rupture of membranes
  • abnormalities of the uterus eg. fibroids
  • excessive amounts of amniotic fluid
  • moderate to severe anaemia early in the pregnancy
  • abdominal surgery during pregnancy
  • abnormalities in the baby

Recognising preterm labour

As with any full term labour there are signs and symptoms you may experience that indicate your labour has started.


You may have been feeling your uterus tighten throughout your pregnancy. These are usually Braxton Hicks contractions which are quite different to the painful contractions of labour. Labour contractions commonly last more than 30 seconds and are regular. Labour may also start as lower tummy pain or constant lower backache (that aching, heavy feeling that some women get with their monthly period).

After sexual activity your uterus may be irritable and you may experience some tightenings which quickly settle.

If you are less than 37 weeks pregnant, labour may progress more quickly than term labour. Please telephone Mater Mothers' Hospitals Birth Suite on 07 3163 1918 or your midwife or doctor as soon as you are aware of regular contractions.


When the plug of mucus in the cervix, which has helped to seal the uterus during pregnancy, comes away as vaginal discharge, it is called a ‘show’. A show’ can be an early sign of labour, but equally it can happen weeks before labour starts. The mucus is usually stained with old blood, and is not usually of concern. However any fresh blood loss, especially if it is not mixed with mucus should be reported to your midwife or doctor immediately.

Rupture of membranes

The bag of amniotic fluid in which the baby is floating may break before labour starts. This is known as ruptured membranes your ‘waters breaking’. If this happens you will notice either a slow trickle or a sudden gush of fluid from your vagina that you can’t control. If this happens use a clean sanitary pad (not a tampon) to absorb the fluid and telephone Mater Mothers' Hospital Birth Suite on 07 3163 1918 or your midwife or doctor. They will ask about the amount of fluid, the colour of the fluid (straw-like or yellowish like urine), its smell (sweet smelling or ammonia smelling), your baby’s movements and your pregnancy history to date.

Management of threatened preterm labour

You will be assessed and examined by a midwife and a doctor and this will include:

  • monitoring of your baby’s heart beat with a cardioticigraph (CTG) machine
  • A speculum examination to see whether your cervix is opening and/or if your waters have broken
  • Observations of your contractions

There are tests which can help identify whether preterm birth is likely and may include a swob from the vagina or a scan.

Possible treatment

As preterm labour can progress more quickly than term labour if you are considered to be at risk of preterm birth, you will be admitted to hospital for continued observation and management.

If you are between 24 and 34 weeks pregnant you will be offered two steroid injections 12 hours apart. Steroids are given to improve lung maturity in premature babies and take about 24-hours to be effective. This is to reduce breathing difficulties after birth.

You may be given some tablets (nifedipine) to help slow or stop labour. This is a smooth muscle relaxant and therefore helps to stop the muscles of the uterus contracting.

Women who are less than 30 weeks and at risk of preterm birth may be offered treatment of magnesium sulphate. This given intravenously over 24 hours—improves the chances of your baby surviving and reduces the risk of neonatal complications.

If your labour continues

If your labour cannot be stopped your baby may be born early. If your baby is presenting head first and there are no other concerning factors a vaginal birth is likely. However, a ceasarean birth may be recommended in a variety of situations if this is thought to reduce the risk to you or your baby.  It is likely that your baby will need to be cared for in the Neonatal Critical Care Unit at Mater Mothers' Hospitals.

Whenever possible a specialist neonatal doctor will come and talk to you before the birth of your baby. They will discuss the care that your baby will need and the chances of your baby having any long term complications.

If your labour stops

If your condition stabilises and you go home, you may be advised to avoid sex until your baby is born. Please discuss this with your midwife or doctor.

If you think you may be in preterm labour, it is important that you contact your midwife or Mater Mothers' Hospital Birth Suite immediately on telephone 07 3163 7000.

© 2014 Mater Misericordiae Ltd. ACN 096 708 922

Mater acknowledges consumer consultation in the development of this patient information.
Mater Doc Num: PI-CLN-430056
Last modified 18/3/2020.
Consumers were consulted in the development of this patient information.
Last consumer engagement date: 28/2/2014
For further translated health information, you can visit healthtranslations.vic.gov.au/ supported by the Victorian Department of Health and Human Services that offers a range of patient information in multiple languages.
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