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Prevalence, Survival and Recurrence Risk


  • In England and Wales in 2013, the rate was 0.3 per 1,000 for trisomy 13 and 0.7 per 1,000 births for trisomy 18.1
  • Maternal age is the major known risk factor for both syndromes.2
  • Due to high levels of prenatal detection and subsequent termination only around 9% of diagnoses in England and Wales result in a live birth.3
  • A high proportion of pregnancies diagnosed with trisomy 18 and trisomy 13 at 12 weeks will end in miscarriage.4
  • The most common forms are full trisomy 18 and full trisomy 13.3
  • From 2004-2011 cases of partial T13 (Robertsonian translocations) accounted for more than 10% of live births with trisomy 13 in England and Wales. There were no recorded cases of partial trisomy 18.3
  • Mosaicism was rare - 17 newborns had T18 mosaicism and only 5 had T13 mosaicism.3

Median survial

  • Median survival times for live births with full trisomy 18 (14 days) and full trisomy 13 (10 days) are similar.3
  • Despite the low median survival time almost 20% of live born infants with either condition do survive for three months and 8% a year.3

Survival for mosaic or partial cases are better and advice relating to an individual karyotype should be sought from your local genetics service.

Recurrence risk

  • There is a small increased risk of the same trisomy after a previous pregnancy with trisomy 13 or trisomy 18.5
  • There may also be a small increased risk of trisomy 18 or trisomy 13 for women with a previous pregnancy with trisomy 21.5
  • The option of prenatal diagnosis in a subsequent pregnancy should be discussed.5


  1. Morris JK, Springett A. The National Down Syndrome Cytogenetic Register for England and Wales 2013 Annual Report. Queen Mary University of London, Barts and The London School of Medicine and Dentistry.
  2. Savva, GM., Walker, K. and Morris JK. 2010. The maternal age-specific live birth prevalence of trisomies 13 and 18 compared to trisomy 21 (Down syndrome). Prenat. Ding., 30: 57-64
  3. Wu J, Springett A, Morris JK. 2013. Survival of trisomy 18 (Edwards Syndrome) and trisomy 13 (Patau Syndrome) in England and Wales: 2004-2011. Am J Med Genet 161A:2512-2518.
  4. Morris JK, Savvy GM. 2008. The risk of fetal loss following a prenatal diagnosis of trisomy 13 or trisomy 18. Am J Med Genet 146A:827-832.
  5. De Souza E et al 2009. Recurrence risks for trisomies 13, 18, and 21. Am J Med Genet, 149A:2716-2722.

Additional Research

Boghossian NS et al. 2014. Mortality and Morbidity of VLBW Infants With Trisomy 13 or Trisomy 18. Pediatrics. 2014 Feb;133(2):226-35. doi: 10.1542/peds.2013-1702. Epub 2014 Jan 20.

Meyer RE at al. 2016. Survival of children with trisomy 13 and trisomy 18: A multi-state population-based study. Am J Med Genet A. 2016 Apr;170(4):825-37. doi: 10.1002/ajmg.a.37495. Epub 2015 Dec 10.