Screening tests to detect Down's syndrome in unborn babies are ineffective, claims research published today.

Screening tests to detect Down's syndrome in unborn babies are ineffective, claims research published today.

A study covering eight district hospitals in the Wessex region looked at the use of several different screening systems between 1994 and 1999.

It found no evidence that blood tests and ultrasound improved the detection of Down's. Nor did it reduce the need for invasive procedures, such as amniocentesis, which involves piercing the mother's abdomen with a probe to sample the fluid surrounding the foetus.

During the five-year study, 155,501 babies were delivered at the hospitals and 335 cases of Down's were identified.

Seven screening policies were used across the region. They included blood tests, ultrasound, routine anomaly scans, and a combination of different methods.

The researchers, led by Diane Wellesley at Princess Anne Hospital, Southampton, found that 15 per cent of pregnant women were aged over 35 at delivery – more than double the 5 to 7 per cent expected. A total of 58 per cent of babies with Down's syndrome were born to women within that age range.

Districts that used blood tests detected 57 per cent of cases. Those using maternal age plus blood tests or ultrasound detected 52 per cent, and those using the woman's age of 35 or more alongside anomaly scans detected 54 per cent.

A government initiative that plans to make new screening tests universal by 2004, is meant to increase detection rates. But the researchers, who report their results in the British Medical Journal, today, say: "Our findings suggest that the recently announced government initiative ... will not achieve its stated objectives."

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