The Natural History of Trisomy 21: Outcome Data from a Large Tertiary Referral Centre

<b><i>Objective:</i></b> The aim of the study was to prospectively gather data on pregnancy outcomes of prenatally diagnosed trisomy 21 (T21) in a large tertiary referral centre. <b><i>Methods:</i></b> Data were gathered prospectively in a large tertiary referral centre over 5 years from 2013 to 2017 inclusively. Baseline demographic and pregnancy outcome data were recorded on an anonymized computerized database. <b><i>Results:</i></b> There were 1,836 congenital anomalies diagnosed in the study period including 8.9% (<i>n</i> = 165) cases of T21. 79% (<i>n</i> = 131) were age 35 or older at diagnosis. 79/113 (69.9%) women chose a termination of pregnancy (TOP) following a diagnosis of T21. Amongst pregnancies that continued, there were 4 second-trimester miscarriages (4/34, 11.7%), 9 stillbirths (9/34, 26.4%), and 1 neonatal death, giving an overall pregnancy and neonatal loss rate of 14/34 (41.1%). <b><i>Conclusion:</i></b> The risk of foetal loss in prenatally diagnosed T21 is high at 38% with an overall pregnancy loss rate of 41.1%. This information may be of benefit when counselling couples who are faced with a diagnosis of T21 particularly in the context of limited access to TOP.