The Natural History of Trisomy 21: Outcome Data from a Large Tertiary Referral Centre.
Level 4 - case-series / case-control
Single-centre prospective observational cohort / case series without a control group.
PubMed 34583352 · doi:10.1159/000517729
What was done
Data on prenatally diagnosed trisomy 21 (T21) cases were prospectively collected over a 5-year period (2013–2017) at a single tertiary referral centre using an anonymized computerised database to examine termination rates and natural history pregnancy outcomes.
What was found
Across 1,836 congenital anomalies, 165 cases of T21 were diagnosed (8.9%), with 79% of mothers (131/165) aged 35 or older. Among women with decision data, 69.9% (79/113) underwent termination of pregnancy. In the 34 continuing pregnancies, outcomes included 4 second-trimester miscarriages (11.7%), 9 stillbirths (26.4%), and 1 neonatal death, resulting in an overall pregnancy and neonatal loss rate of 41.1% (14/34; fetal loss rate 38.2%).
Why it matters
These natural history data quantify the substantial risk of spontaneous fetal and neonatal loss in continuing T21 pregnancies, providing baseline figures for prenatal counselling.
Limits
The natural history analysis was restricted to a small continuing-pregnancy subcohort (n = 34) due to high termination rates. The study was conducted at a single tertiary centre, which may overrepresent high-risk cases, and outcome data were not reported for the full initial cohort of 165 cases.