I applaud the Ministry of Health's (MOH) decision to permit clinical trials for pre-implantation genetic screening (PGS) of in-vitro fertilised embryos ("Trial for screening IVF embryos to start soon"; Nov 11).

While there is recent scientific and clinical evidence to suggest that such screening may be beneficial for patients with recurrent miscarriages and repeated IVF failures, the ministry should implement safeguards to prevent its non-judicious use.

Currently, numerous private fertility clinics worldwide are calling for the universal application of PGS for all older women undergoing fertility treatment, regardless of whether they have any medical history of miscarriages or failed IVF treatments.

The reasoning is that older women have higher chances of giving birth to a baby with genetic abnormalities, such as Down syndrome.

While this is an indisputable scientific fact, there is a risk that many healthy older women embarking on their first IVF cycle, without any previous miscarriages, may be cajoled into opting forsuch an expensive and complex procedure because of aggressive marketing by fertility clinics.

In particular, a patient may be misinformed by the concept of relative risks.

For example, if the chance of having a Down syndrome baby is 0.1 per cent, 0.3 per cent and 1.2 per cent for women aged 25, 35 and 40, respectively, then an alternative way of presenting the risks is to tell them that the chances of having a Down syndrome baby increases three times by the age of 35, and 12 times by the age of 40, even though the actual risks of having a Down syndrome baby by older women are still very low.

Hence, by the manipulation of words and figures, the risks may be exaggerated to patients, to "scare" them into opting for such an expensive and complex procedure.

Moreover, it must be noted that with PGS, there is a risk of damaging the embryo, as it is a highly complex and delicate procedure. Patients opting for this procedure should be told about this.

Hence, MOH should implement safeguards such as appropriate counselling on the relative risks, to ensure judicious use of PGS only when it is truly warranted.

Alexis Heng Boon Chin (Dr)