Women who are regularly exposed to the highest levels are around three times more likely to miscarry than someone whose exposure is low.
Magnetic fields from mobiles, wi-fi, other wireless devices and power lines produce non-ionizing radiation, and this seems to have "adverse biological impacts on human health," said researcher Dr De-Kun Li from the Kaiser Permanente Division of Research.
The discovery has wider implications, and could be further confirmation that cell phones can cause cancer, although Dr Li said he was unable to prove this from the short-term study he carried out.
A group of 913 pregnant women carried a monitoring device for 24 hours and kept a diary of their activity, and their pregnancy was then tracked. Around 10 per cent of the women exposed to the lowest levels of radiation miscarried—which is similar to the miscarriage rate in the general population—but the rate rose to 24 per cent among women who were exposed to the highest levels.
Because of the short time-scale of pregnancy, Dr Li said he was able to track the impact of radiation, but assessing whether or not it causes chronic problems such as cancer and auto-immune diseases would require a much longer time frame.