BBC News:  Friday, 6 September, 2002, 14:15 GMT 15:15 UK

A test which can measure the electrical signals in the foetal brain could one day help doctors protect babies from damage sustained in the womb.

It is one of the first times that the activity of the brain has been measured, and showed that foetuses could even respond to a bright light shining through their mothers' abdomen.

The research, carried out by scientists at the University of Arkansas, in the US, used a technique called magnetoencephalography (MEG).

Nerve activity in the brain involves tiny electrical impulses, and this technique relies on the principle that even the smallest of these creates a magnetic field.

The device employed by the researchers can measure miniscule fluctuations in magnetic fields using a superconductor cooled by liquid helium.

To test the device, 10 pregnant women with foetuses aged between 28 and 36 weeks leaned into an array of 151 sensors around their "bumps".

A fibreoptic cable was then used to deliver light pulses - about 11 times less intense than sunlight on a bright day.

The mother and the foetus both produce a strong magnetic signal because of the electrical discharges from their respective heart beats, but scientists were able to screen these out and look instead for signs of a response to the flashing light.

Sleeping brains

Four out of the 10 foetuses had measurable brain responses to the light, with reaction times better in the more highly developed foetuses.

The scientists did not believe that no response from the other six was a reason for concern, they may simply have been asleep or facing in the wrong direction.

The practical benefits of this scanning system could prevent, or at least lessen brain deficits caused by lack of nutrients from the placenta.

A frequent cause of disability is that the placenta - the link between the blood supply of foetus and mother - is "starving" the baby of the nutrients essential for proper brain development.

In some cases, this may cause the baby to be born with a brain defect such as cerebral palsy.

If "placental starving" is suspected, in some cases it might be better, later in pregnancy, to deliver the baby prematurely - but premature babies face other risks, and it is hard to judge which course of action is for the best.

A test which could determine the level of foetal brain activity might help doctors make this decision.

Research chance

Dr Penny Gowland, from the University of Nottingham, believes that this is the most obvious potential benefit of the technique.

She said: "It is a fascinating area, and very little is understood about how the foetal brain develops. This kind of thing may help us do that.