Premature birth statistics

A preterm birth, one that happens before 37 completed weeks of pregnancy, is the number one cause of newborn deaths and the second leading cause of deaths in children under five.

Pre-term birth statistics

Preterm birth, which occurs before 37 completed weeks of pregnancy, is the biggest cause of newborn deaths and the second biggest cause of deaths in children under five.

What is preterm birth?

Preterm babies are at increased risk of illness, disability and death. The World Health Organisation gives the following definitions for the different stages of preterm birth:

• extremely preterm: before 28 weeks

• very preterm: from 28 to 32 weeks

• moderate to late preterm: from 32 to 37 weeks.

In the UK, around 60,000 babies are born prematurely each year. Globally, more than 1 in 10 pregnancies will end in preterm birth (and this number is rising).

What are the chances of survival following preterm birth?

• In babies born preterm, the chance of survival at less than 22 weeks is close to zero. At 23 weeks it is 19%, at 24 weeks 40%, at 25 weeks about 66% and at 26 weeks 77%.

• In 2015, there were over 850 deaths of babies born at 22 and 23 weeks.

• Globally, premature birth is the biggest global killer of young children, with more than 1 million children dying each year due to the complications of preterm birth, mostly in the developing world.

Survival rates of preterm birth

Survival increases for each week the baby stays in the womb. Those born alive at 27 weeks have an 87 per cent chance of surviving, at 28 weeks it is 92 per cent and at 29 weeks, 95 per cent.

Causes of preterm birth

In many cases the reason for the premature birth is unknown. The reasons below can overlap.

• 25% of preterm births are planned because the mother and/or baby are suffering life-threatening complications such as pre-eclampsia, kidney disease or growth restriction.

• 40% are linked to waters breaking early (premature rupture of the membranes).

• 25% are linked to an emergency event, for example, placental abruption (when the placenta detaches itself from the uterus), infection, eclampsia or prolapsed cord (when the umbilical cord exits the body before the baby).

• In 40% of cases the cause is not known

What are the links between multiple pregnancies and preterm birth?

Studies show that the length of gestation typically reduces with each additional baby. On average, most singleton pregnancies last 39 weeks, twin pregnancies 36 weeks, triplets 32 weeks, quadruplets 30 weeks and quintuplets 29 weeks. Almost 60% of twins are born preterm, while 90% of triplets are preterm.

Read more about our research into premature birth

  • Clinician scanning a pregnant woman

    The London Preterm (premature birth) Surveillance Clinic

    This unique Preterm Surveillance Clinic – funded by Tommy's as part of our research in St Thomas' Hospital, London, has won an NHS Innovation Challenge Prize, for its success in reducing the number of premature births in South East London.

  • researcher looking at samples in the Tommy's London centre

    Tommy's London research centre

    Tommy’s prematurity research centre in London is based at St Thomas’ Hospital, where the charity first began. Opened in 1995, it is the first Maternal and Fetal Research Unit in the UK.

Why our work is necessary



[1] World Health Organisation (2015) Preterm birth Available at: (accessed 2 February 2016).

[2] World Health Organisation (2015) Preterm birth Available at: (accessed 2 February 2016).

[3] British Medical Journal (2016) Available at 

[4] MBRACE-UK (2017) Perinatal Mortality Surveillance Report Available at: (accessed 28th June 2017)

[5] World Health Organisation (2015) Preterm birth Available at: (accessed 2 February 2016)

[6] British Medical Journal (2016) Available at 


[8] American Pregnancy Association. Complications in a multiples pregnancy. Available at: (accessed 19 February 2016).


ISD Scotland (2016) Births in Scottish Hospitals. Information Services Division, NHS National Services Scotland.

NSRA Northern Ireland (2015) Registrar general annual report. Northern Ireland Statistics and Research Agency, Belfast, Northern Ireland

Cloherty JP. Care of the extremely low birth weight infant. Manual of neonatal care (7th edn). Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, 2012.

National Institute for Health and Care Excellence (NICE). Preterm labour and birth. London: NICE, 2013. Available at: (accessed 2 February 2016).

Henderson C, Macdonald S. Mayes midwifery: a textbook for midwives. Philadelphia: Bailliere Tindall, 2011.

Costeloe KL, Hennessy EM, Haider S, et al. Short-term outcomes after extreme preterm birth in England: comparison of two birth cohorts in 1995 and 2006 (the EPICure studies). BMJ 2012;345:e7976.

Hide details