Recent trends in the prevalence and secondary prevention of Down's syndrome

TLDR

Between 1974 and 1986, 184 Down's syndrome infants were born in Greater Glasgow, giving a period prevalence of 1.1 per 1,000 births, with most cases in mothers under 35, no recent decline in prevalence or shift in maternal age risk, and antenatal diagnosis leading to termination in less than 10% of pregnancies. These findings highlight the need for further etiological research, ongoing epidemiological surveillance, improved amniocentesis uptake among older mothers, and development of a universal screening test.

Abstract

Examination of data from the Glasgow Registry of Congenital Anomalies indicated that 184 infants with Down's syndrome were born (live or still) to mothers residing in the Greater Glasgow Health Board area between 1974 and 1986 inclusive. This represents a period prevalence of 1.1 per 1000 total births. Despite a strongly positive correlation between prevalence and maternal age, most of the Down's syndrome infants were born to mothers aged under 35 years. There was no evidence either of a recent decline in the annual prevalence rate or of a changing pattern of risk in relation to maternal age. Antenatal diagnosis resulted in the termination of less than a tenth of all Down's syndrome pregnancies. These findings point to a need for further aetiological research, for continued epidemiological monitoring, for an improvement in the relatively low uptake of amniocentesis by older mothers, and for the development of a screening test which can be offered to the entire pregnant population.