Antenatal detection of Edwards (Trisomy 18) and Patau (Trisomy 13) syndrome: England and Wales 2005-2012.

OBJECTIVES

Pregnancies with Edwards or Patau syndrome are often detected through screening for Down's syndrome. We aimed to evaluate the impact of screening for Down's syndrome on the prevalence of live births and antenatal diagnoses of Edwards and Patau syndrome.

SETTING

England and Wales, 2005 to 2012.

METHODS

Data from the National Down Syndrome Cytogenetic Register, which contains information on nearly all ante- or postnatally diagnosed cases of Edwards or Patau syndrome in which a karyotype was confirmed, were analysed.

RESULTS

From 2005 to 2012, 3,941 diagnoses of Edwards syndrome and 1,567 diagnoses of Patau syndrome were recorded (prevalence of 7.0 and 2.8 per 10,000 births respectively). Only 11% (95% confidence interval [CI]: 10-12) of diagnoses of Edwards syndrome and 13% (95% CI: 11-14) of Patau syndrome were live births, resulting in live birth prevalences of 0.8 (95% CI: 0.7-0.8) and 0.4 (95% CI: 0.3-0.4) per 10,000 live births respectively. About 90% of pregnancies with Edwards or Patau syndrome were diagnosed antenatally, and this proportion remained constant over time. The proportion of diagnoses detected before 15 weeks increased from 50% in 2005 to 53% in 2012 for Edwards syndrome, and from 41% in 2005 to 63% in 2012 for Patau syndrome.

CONCLUSIONS

Almost 700 women per year had a pregnancy with Edwards or Patau syndrome. Over 90% of these pregnancies were detected antenatally, with the increased use of first trimester screening for Down's syndrome resulting in the reduction in the mean gestational age at diagnosis of these syndromes.