Millennium bug caused error in Down's screening

Four women gave birth to Down's syndrome babies after a hospital's failure to guard its computer software against the millennium bug resulted in 150 incorrect pre-natal screening results.

Four women gave birth to Down's syndrome babies after a hospital's failure to guard its computer software against the millennium bug resulted in 150 incorrect pre-natal screening results. Two other women made belated decisions to have abortions.

The error, which went undetected for four months at the Northern General Hospital in Sheffield, meant the women – most of whom were aged over 35 – were originally told they were at low risk of giving birth to a Down's child when in reality they were high risk. The consequences were revealed in a report commissioned and overseen by Professor Lindsey Davies, the Trent regional director of public health, and published yesterday. The 150 women given inaccurate results are known to have been between 18 and 35 weeks pregnant.

The 112-page report concluded that the previous success of the hospital's pre-natal screening service had "led to a degree of overconfidence in the processes used and the software which contributed to the warning signs being overlooked and accommodated as acceptable errors".

When the results appeared odd, the hospital "just thought it was a different mixture of women coming through, rather than the computer software."

The computer did not calculate the mother's age correctly because of the millennium bug, the report stated. The late detection of the Down's risk also meant a critical delay in subsequent amniocentesis tests for Down's.

The women affected by the error were among 4,000 given a routine blood-screening test between the 14th and 18th weeks of pregnancy at nine hospitals in South Yorkshire, Lincolnshire and the East Midlands. The error, which covered the period from 4 January to 24 May last year, was finally detected during a routine audit.

Andrew Cash, chief executive of Sheffield Teaching Hospitals NHS Trust, which manages the hospital, apologised yesterday to the families affected.

The Down's syndrome Association stressed the tests provided no guarantees and urged prospective parents not to make screening an automatic consideration.

Sarah Leggat, of Maidstone, Kent, is a mother who declined tests and gave birth to a daughter, Georgia, who has Down's. She said: "It's important to ask 'do I need the [screening] information?' Hospitals are pushing mothers into it."