ULTRASOUND scanning can pick up pregnancies most at risk of Down's syndrome as early as 11 weeks, according to a specialist in foetal medicine. Dr Kypros Nicolaides, professor at King's College Hospital, London, says the preliminary results of a study he is conducting suggest that about 90 per cent of babies born with Down's syndrome have a fluid- filled space behind the neck that can be detected early.

In a report in General Practitioner, Dr Nicolaides estimates that any woman whose scan reveals the presence of the fluid runs a risk of having a Down's syndrome baby 10 times higher than that calculated by maternal age alone, and should be offered further antenatal tests. He is hoping to screen 20,000 women before the end of the year to confirm his results.