NCARDRS Congenital Condition Official Statistics Report, 2022

Confirmation of a condition relates to a definitive diagnosis from a genomic test and as such represents a confirmed diagnosis (for further information see the Technical details, section 3). This is distinct from detection, which requires only the clinical suspicion of the condition. 

Figure 6 and Data table 6 show the number of trisomies, categorised by timing of confirmation for Down’s syndrome, Edwards’ syndrome and Patau’s syndrome. Where timing of confirmation was known, 60.0% (N=1,024) of babies with Down’s syndrome, 71.7% (N=353) with Edwards’ syndrome and 61.4% (N=121) with Patau’s syndrome were confirmed antenatally.

Postnatal diagnoses include babies where the woman has chosen to decline antenatal screening or diagnostic cytogenetic tests but will also include testing performed following a late miscarriage, termination or stillbirth as well as live birth.

Figure 7 (Data table 7) shows timing of confirmation by geographical region. There is variation in the timing of confirmation across the regions. The proportion of trisomy conditions that were confirmed antenatally ranged from the lowest percentage in the North East (53% of babies diagnosed antenatally, 95% CI 45.8-65.4) to the highest percentage in the South East (71.4% of babies diagnosed antenatally, 95% CI 66.9-75.5). There are likely to be several reasons behind this, including, differences in the population, differences in the age of the woman and coverage of screening. Where a baby has had both an antenatal and a postnatal diagnostic test, the earlier diagnosis is taken as the point of ascertainment.