Down's syndrome: occurrence and outcome in the north of England, 1985-99.

This study reports changes in the prevalence and outcome of Down's syndrome pregnancies within a 15-year period in a defined geographical population in the north of England. Cases of Down's syndrome in births and terminations of pregnancy occurring between 1985 and 1999, were identified from the Northern Congenital Abnormality Survey. The total prevalence for the 15 years was 15.2 per 10 000 births and terminations of pregnancy [95% CI 14.2, 16.2]. Total prevalence showed an upward trend over time, due largely to increasing maternal age. Sixty-seven per cent of cases resulted in live births, and the overall live birth prevalence was 10.3 per 10 000 live births [95% CI 9.4, 11.1]. The proportion of cases resulting in termination of pregnancy rose from 15% in 1985-89 to 38% in 1995-99; the rate of increase was greater in women aged < 35 years. Forty-five per cent of live born infants had an additional anomaly recorded. Survival at 1 year was 78% for those with an additional anomaly recorded, and 96% for those without. There was a non-significant trend towards improved survival in all infants with Down's syndrome, from 87% in 1985-94 to 92% in 1995-99. Despite increasing termination of Down's syndrome pregnancies resulting from the greater availability of antenatal screening and diagnosis, there has been no significant reduction in live birth prevalence. These infants have high rates of co-existing structural anomalies and are at high risk of death in the first year of life. There is a continuing need to address the reasons for poor survival for Down's syndrome infants, and to plan for their complex health and social care needs. These findings are useful for parents deciding on prenatal screening, as well as for clinicians and health service managers.