The UK’s advertising authority has rapped clinics for misleading claims that exaggerated the accuracy of their pre-natal testing and banned the offending advertisements.

Three clinics had marketed their screenings as 99% accurate for Downs syndrome. While the Advertising Standards Authority did find the tests provided false-negatives only 1% of the time, indicating no abnormality even when one is present, the ASA also found the tests provided false positives, indicating Downs syndrome is present even when it is not, up to 18% of the time.

The clinics also marketed a test for Patau’s syndrome as 93.8% accurate, even though it provided false positives up to 51% of the time.

Testing for Edwards’ syndrome provided false positives 63% of the time.

The ASA said: “We understood that a systematic review of the performance of non-invasive prenatal testing in general found that it had a Positive Predictive Value (PPV) of 82% for Down’s syndrome, 37% for Edwards’ syndrome and 49% for Patau’s syndrome, meaning out of all the foetuses with ‘positive’ results, 82% would ultimately have Down’s syndrome, as opposed to the 99% detection rate figure that consumers would understand from the ad.”