Updated February 2014

Premature birth statistics

Definitions

Preterm birth, which occurs 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. Preterm babies are at increased risk of illness, disability and death [1]. The World Health Organization gives the following definitions for the different stages of preterm birth [1]:

  • extremely preterm: < 28 weeks
  • very preterm: from 28 to < 32 weeks
  • moderate to late preterm: from 32 to < 37 weeks.

Incidence in the UK

  • England and Wales: in 2012, 7.3% of live births were preterm (under 37 weeks’ gestation). The majority (92.7%) occur after 28 weeks [2].
  • Nearly 85% of all babies born prematurely will have a very low birthweight (under 1,000g), compared to 94% of babies born under 24 weeks [2].
  • Preterm birth rates in England and Wales have remained steady (7.3% in 2009, 7.1% in 2010, 7.2% in 2011 and 7.3 in 2012).
  • In 2012, the infant mortality rate for babies born preterm (between 24 and 36 weeks) was 23.6 deaths per 1,000 live births, 15.5% lower than the rate for preterm babies born in 2008 (27.6 deaths per 1,000 live births) [2].
  • In England and Wales, in 2012, 10% of preterm births were to mothers aged 40 and over, compared to 6.8% in mothers aged 20-24 [2]. For babies born in 2012, only 6% of singleton births were preterm, compared with more than half (56%) of multiple births [2].
  • In 2012, the infant mortality rate for babies born preterm was higher for single births than for multiple births (24.8 and 19.9 deaths per 1,000 live births respectively) [2].
  • Scotland: the percentage of preterm (born before 37 completed weeks) singleton babies rose from 5.2% in 1975/76 to a peak of 6.7% in 2003/04 and fell to 5.9% in 2011/12 [3].
  • Northern Ireland does not currently compile figures on premature births.

Global incidence 

  • Globally, 15 million babies are born preterm every year and this number is rising. This is more than 1 in 10 births [1]. The rate of preterm births has increased over the last 20 years. It is thought this this is because of increased maternal age (and maternal problems such as diabetes and high blood pressure), increasing rate in pregnancy-related complications, such as gestational diabetes, greater use of infertility treatments leading to more multiple pregnancies and more caesarean deliveries taking place before term [1].
  • Premature birth is now 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 [1].

Causes

  • 25% of preterm births are planned caesarean sections because the mother might have severe pre-eclampsia, kidney disease, or because the baby is not developing properly [4].
  • 20% of cases are due to premature rupture of the membranes [5].
  • 25% of cases will be due 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) [5].
  • In 40% of cases, the cause is not known [5].

Read more about the causes of premature birth here.

Survival rates

  • In England, survival rates of very premature babies increased from 40% in 1995 to 53% in 2006 [6].
  • Survival increases by 9.5% for each week if the baby is born at 23 weeks, and 16% per week if the baby is born at 25 weeks [6].
  • Survival rates for the rest of the UK countries are not available.

Risk factors

Often, the specific cause of premature birth is not clear. However, many factors may increase the risk of premature birth.

  • Having more than two preterm deliveries increases the risk of another premature baby by 70% [5].
  • An abnormally shaped uterus increases the risk of giving birth early by 19% [5].
  • Women are nine times more likely to give birth early if they have a multiple pregnancy (twins, triplets) [7].
  • An interval of less than 6 months between pregnancies [7].
  • Conceiving through in vitro fertilisation [7].
  • Smoking, drinking alcohol and using illicit drugs [7].
  • Poor nutrition, some chronic conditions (high blood pressure, diabetes), multiple miscarriages or abortions are also known risk factors [7].

Health outcomes

More babies survive premature birth, but serious health problems remain unchanged [8]. Between 1995 and 2006 survival shortly after birth of very premature babies has increased by 13% (from 40% in 1995 to 53% in 2006), but the proportion of survivors leaving hospital with major health problems is unchanged [8]. Preterm birth is associated with [5]:

  • Respiratory complications and lung disease
  • Problems with bowel function
  • Long-term neurological damage

Read about your premature baby's time in hospital here

Long-term outcomes

A study following the progress of very premature babies (born before 27 weeks) in the United Kingdom and Ireland (EPICure study) found a high level of disability once the children reached 6 years of age [8]:

  • 22% had severe disability (defined as cerebral palsy but not walking, low cognitive scores, blindness, profound hearing loss)
  • 24% had moderate disability (defined as cerebral palsy but walking, IQ/cognitive scores in the special educational needs (SEN) range, a lesser degree of visual or hearing impairment)
  • 34% had mild disability (defined as low IQ/cognitive score, squint or refractive error, requiring glasses)
  • 20% had no problems.

When children born before 26 weeks were re-assessed in middle childhood (aged 11 years), the researchers found that 45% had serious cognitive impairment. The following academic attainment was found [9]:

  • They had significantly lower scores for cognitive ability, reading and mathematics
  • 13% attended special schools
  • 57% of those in mainstream schools had SEN
  • Those who entered school an academic year early due to preterm birth had similar academic attainment but required more special needs support

Visit our section on premature birth



Sources

[1] World Health Organization (2014) Preterm birth. Fact sheet No. 363. Geneva: WHO, 2014. Available at: http://www.who.int/mediacentre/factsheets/fs363/en/ (accessed 9 December 2014).

[2] Office for National Statistics (2014) Gestation-specific infant mortality, 2012. Cardiff: ONS, 2014. Available at: http://www.ons.gov.uk/ons/publications/re-reference-tables.html?edition=tcm%3A77-349394 (accessed 9 December 2014).

[3] Information Services Division. Births in Scottish hospitals: year ending 31 March 2012. Edinburgh: ISD Scotland, 2013. Available at: http://www.isdscotland.org/Health-Topics/Maternity-and-Births/Publications/2013-08-27/2013-08-27-Births-Report.pdf?34511965514 (accessed 9 December 2014).

[4] National Institute for Health and Care Excellence. Preterm labour and birth. London: NICE, 2013. Available at: http://www.nice.org.uk/guidance/indevelopment/gid-cgwave0660/documents (accessed 9 December 2014).

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

[6] 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.

[7] Mayo Clinic. Premature birth. Available at: http://www.mayoclinic.org/diseases-conditions/premature-birth/basics/risk-factors/con-20020050 (2014, accessed 9 December 2014).

[8] Marlow N, Wolke D, Bracewell MD, et al. Neurologic and developmental disability at six years of age after extremely preterm birth. New England Journal of Medicine 2005;352(1):9-19.

[9] Johnson S, Hennessy EM, Smith R, et al. Academic attainment and special educational needs in extremely preterm children at 11 years of age: the EPICure study. Archives of Disease in Childhood. Fetal and Neonatal Edition 2009;94(4):F283–9.


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Employment
Lifestyle statistics

Miscarriage statistics

Pre-eclampsia statistics

Premature birth statistics

Stillbirth statistics

Toxoplasmosis statistics


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Definitions

Incidence

Causes

Survival rates

Outcomes



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