Down's test anguish for 154 women after error

More than 150 pregnant women have been given test results telling them they were at low risk of giving birth to a Down's syndrome baby when they were actually at high risk.

More than 150 pregnant women have been given test results telling them they were at low risk of giving birth to a Down's syndrome baby when they were actually at high risk.

A computer software error, which went undetected for four months at the Northern General Hospital NHS Trust in Sheffield, means 154 women - most of whom are aged over 35 - were wrongly advised because the principal factor in Down's cases, their age, was not correctly accounted for.

Now the women, who are in the 18th to 35th week of pregnancy, must decide whether to have an amniocentesis test for Down's - incurring a slight risk of miscarriage - and even consider a termination in the event that severe handicap is detected. The hospital pointed out that termination would still be permissible in law even if the woman was more than 24 weeks pregnant - the period beyond which some consultants consider it unacceptable.

Debra Royston, 32, from Sheffield, was told five weeks ago that she had a 1 in 570 risk of carrying a Down's child. The odds have now been recalculated at 1 in 150, and the miscarriage risk of amniocentesis is greater because the baby is bigger. "I got a letter at 17 weeks saying I was low risk and we thought everything was OK," she said yesterday. "Now I have been told I am a high risk. I just got a note in my pre-natal book apologising for the mistake. If I have the test now I risk losing a perfectly healthy child. Having the test at this late stage is a major worry. I don't know what I am going to do." She plans to take legal advice and may sue for damages.

Most of the women affected by the error were given a routine blood-screening test between the 14th and 18th weeks of their pregnancy. The hospital's department of immunology's Pathlan software system, which is not used for the same purpose by any other British hospital, factors in the blood test results - with the mother's age, body weight and length of pregnancy.

John Watts, acting chief executive at the Northern General, said: "What we know at this stage is that it was the variable of age that was causing the problem. It does not follow that the women concerned will give birth to a Down's syndrome baby, but they are at a higher risk of doing so."

The trust, which conducts 18,000 similar blood tests a year, said it was impossible to determine how many of the women would go on to have Down's babies, though nationally 1.3 per 1,000 women in the high-risk category do. The risk increases with age.

Mr Watts said the software glitch covered the period from 4 January to 24 May, during which time 4,000 women were tested. It was detected during a routine audit and action had been taken to correct it.

The trust performs the tests for a number of hospitals in the surrounding area - Barnsley District General Hospital, Chesterfield and North Derbyshire Royal Hospital, Doncaster Royal Infirmary, Grimsby Maternity Hospital, the Jessop Hospital for Women and the Northern General Hospital in Sheffield, Rotherham District General Hospital, Scunthorpe General Hospital and Worksop Hospital.

The trust said all 154 women should have been contacted by the end of today.