London, May 11: Life-saving incubators may impede the development of the nervous system among infants which can lead to cot death, a research has suggested.

Incubators, which are used to keep the babies warm and decrease the chance of infection, have motors that create electromagnetic fields in the area where they lie.

The study, which is published in the current issue of the 'Fetal and Neonatal Edition of Archives of Disease in Childhood,' shows that even the very low electrical fields given off by the incubators interfere with infants' heart rates, which in turn impedes the development of the nervous system that can lead to cot death.

The research at the General Hospital of the University of Siena, Italy, found these fields cut the variability of babies' heart rates in half. Reduction in variability is thought to be an indicator of heart disease in adults.

"What we have proved is that the effects of these machines are not neutral and they should be. The manufacturers of these incubators should take steps to shield babies from their motors and to move motors further away within the machine," said Professor Carlo Bellieni, who led the research.

The findings will deepen concerns about the danger of "electrosmog" given off by electrical equipment which is thought to interfere with the tiny currents that help to drive the human body and govern the heart, The Independent daily of Britain said.

It could also imply that placing infants near electrical devices including clocks and radios may be dangerous for their health. Many researchers have linked electromagnetic fields with asthma and other respiratory diseases, and cancer, the report said.