'We would discourage women from sharing food.' Picture: Max Pixel

London - Finishing off your young child’s dinner or giving them a kiss goodnight is part and parcel of any busy parent’s day.

But pregnant women have been warned off these seemingly harmless habits – as they could pass on a "stealth virus" to their unborn child.

CMV, or cytomegalovirus, can be transmitted through children’s saliva – often found on part-eaten food and picked up through kissing.

Scientists at St George’s, University of London have warned that it affects around 1 000 babies a year and may put them at risk of cerebral palsy, deafness and developmental delay. Project leader Dr Chrissie Jones last night said: "The most important message is not to come into contact with the saliva of a young child.

"We would discourage women from sharing food. Don’t kiss your children directly on the lips, kiss them on the forehead."

Experts at St George’s, Kingston University, St George’s University Hospitals NHS Foundation Trust, University College London and Cambridge University hope a trial – in which 400 mothers with a child under three watch a video highlighting the consequences of the virus – will raise awareness.