PA -- Newborn babies’ heart rates are altered by the electromagnetic fields given off by incubators, a new study has found.Researchers warn this could have implications for premature babies, who can spend weeks or even months in incubators.Scientists from the University of Siena in Italy tested the heart rate of 43 newborn babies, none of them seriously ill or premature, between March and August last year. They found that the infants’ heart rate variability (HRV) fell significantly while the incubator was switched on. Lower HRV is associated with a poor prognosis in patients with heart disease.