The government's genetics watchdog yesterday warned against the dangers of unregulated private clinics offering pregnancy screening.

The Human Genetics Commission (HGC) said the problem was of particular concern in Scotland because of shortages in testing on the NHS.

Speaking at their conference in Edinburgh yesterday members raised worries about private clinics charging expectant mothers for specialist Down's syndrome screening tests. Specialists said such tests, notably the nuchal translucency test which looks at whether the embryo is at risk of developing Down's syndrome, should be conducted by trained, regulated specialists because of the potential distress involved.

Dr Rosalind Skinner, Principal Medical Officer for Scotland, said the issue was of particular concern north of the border because so few NHS services offered the test.

She said unregulated clinics were emerging despite repeated warnings from the National Screening Committee. "One concern is about the quality assurance of tests offered in the private sector," she said. "Very few services offer it on the NHS in Scotland."

Nuchal translucency screening is done at 11 to 12 weeks of pregnancy and involves ultrasound to check the size of a sack of fluid on the back of the baby's neck.

If the sack is greater than 3mm there is an increased risk of Down's syndrome. Those who are told their baby has an increased risk are usually offered a second more invasive test which increases the chances of miscarriage by 1%. Dr Rosemary Leonard, a GP and member of the HGC, said: "When looking at measurements that small it is absolutely vital the person doing the ultrasound knows where to put the markers. It would be easy to get wrong. The lack of regulations on this area is very worrying."

The commission also warned against the limitations of private clinics offering tests to check whether young people were likely to suffer from sudden cardiac death. There have been a number of high-profile cases of young footballers suddenly dropping dead from the condition.

Dr Christine Patch, a consultant genetic counsellor and member of the HGC, said such screening was not offered on the NHS because the ramifications were so serious and the tests were still not 100% predictive.

Members of the commission said there have been examples of private firms going into public schools to offer the tests but warned they should only be used on the NHS for those who have a family member who has been diagnosed with the condition.