World Health Organisation, Treatment and Prevention of Dehydration Due to Diarrhoea-guide for Workers at Primary Level. Geneva, Who. in Press

uneventful pregnancies giving rise to unaffected children had the screening programme been offered to them: a tricky concept. (It is not easy to see how that estimate of cost is obtained from their abbreviated table III.) The cost of permanent care of people born with Down's syndrome relative to that of an assumed normal birth cohort is so low partly because the estimated cost of permanent care of 45-year-olds (the age at which 100°,, of Down's syndrome births are assumed to be in permanent care) is low (about £250 per person per annum) but principally because, when discounted at 1000 per annum for 45 years, it gives a "present value" of only £3 per person per annum. Next they estimate the total (relative) "present value" cost (of caring for people born with Down's syndrome) as £4150 per person per annum. Yet in their summarising paragraph they call this (81 affected births) a benefit and it is discounted a second time at 10% in the calculation of a total programme benefit. This notwithstanding that their calculations suggest for West Scotland a "replacement" benefit of some £350 000 and a "no replacement" benefit of £800 000; in other words society will benefit to the tune of nearly £!m ("present value") by preventing each year eight uneventful pregnancies resulting in eight normal births (after amniocentesis and terminations for the eight affected). This illustrates how a high discount rate makes distant future earnings of the newborn negligible compared with the present costs of infant care and the near future costs of schooling, even in the healthy. One of the benefits that has to be taken into account (even if it is not given a cash value) is the value of life per se.1 The logical conclusion derivable from their calculation is not to screen the over-40s for Down's syndrome but to prevent all births (whether "replacement" or not). ROBERT R WEST