Objective To investigate the influences of survival in children born with Down Syndrome.

Design Population-based case-series derived from the Northern Congenital Abnormality Survey.

Setting A geographically distinct area of Northeast England, incorporating North Cumbria, Northumberland, Tyne and Wear, Country Durham, and the Tees Valley.

Participants 1101 individuals with Down Syndrome delivered between 01 January 1985 and 31 December 2003, of whom 697 were live born and 664 (95%) were traced for their survival status on 28 January 2008.

Main outcome measures Overall prevalence of Down Syndrome. Frequency of additional structural anomalies among cases of Down Syndrome. 10-year survival for all cases of Down Syndrome, by time-period, and by presence, and type, of additional structural anomalies. Independent influence of year of birth, sex, plurality, gestational age, birthweight (standardised for sex, plurality, and gestational age), maternal age, index of multiple deprivation, prenatal diagnosis, and presence, and type, of additional structural anomalies on survival.

Results Overall prevalence of Down Syndrome was 16.7 per 10 000 registered births (95% CI 15.6 to 17.6). 697 (63%) cases had no additional structural anomalies, 320 (29%) had isolated cardiovascular anomalies, 27 (2%) had isolated digestive system anomalies, 26 (2%) had both cardiovascular and digestive system anomalies, and 31 (3%) had at least one other structural congenital anomaly. 10-year survival among children born with Down syndrome was 83.9% (95% CI 80.9 to 86.5). Survival increased significantly with time (p<0.001), from a 10-year survival of 78.2% (95% CI 72.4 to 83.0) in 1985–1990 to 91.1% (86.7 to 94.1) in 1997–2003. Presence of an additional structural anomaly significantly reduced survival (p<0.001) from a 10-year survival of 94.1% (95% CI 90.9 to 96.1) among those with no additional anomaly to 75.2% (69.5 to 80.0), 68.4% (42.8 to 84.4), 54.2% (32.7 to 71.4), and 76.9% (44.2 to 91.9) among those with cardiovascular anomalies, digestive system anomalies, both cardiovascular and digestive system anomalies, and at least one other structural anomaly respectively. Of the other factors examined, only gestational age (p<0.001) and standardised birthweight (p=0.008) also independently predicted survival.

Conclusion Independent of significant improvement over time, survival of children born with Down syndrome is influenced by gestational age, birthweight, and the presence of additional structural anomalies. This information will be valuable for families and health care professionals when Down Syndrome is detected, and will assist in planning, assessing, and aiding, the future care needs of those affected.