The prospects for "preventing" Down's syndrome in an English region

In the Trent Region, changes in the number and maternal age of livebirths have had a marked effect on the estimated number of Down's births. These changes mean that, if pre-natal screening had been available in 1963, one half of all Down's syndrome livebirths could have been detected by screening all mothers in the age group 35 years and above. Currently, however only about a quarter of livebirths with Down's syndrome is potentially detectable by screening this same age group. Using projections for future years, it seems likely that about 28 to 33% of Down's syndrome livebirths will be potentially detectable by screening mothers aged 35+. The prospects for "preventing" Down's syndrome suggested by demographic data alone also have to be considered in the light of the accuracy and safety of the tests, the service offered, acceptance of the procedure, cost-benefit analysis and ethical issues.