Babies exposed to relatively high magnetic fields in the womb are significantly more likely to be overweight or obese later in childhood, new research suggests.
The Kaiser Permanente study, reported online in the journal Nature's Scientific Reports, linked in-utero magnetic-field exposure to a 69 percent increase in the risk of being overweight in childhood.
"Pregnancy is a critical developmental stage that is among the most vulnerable periods to environmental exposures," said lead researcher Dr. De-Kun Li, an epidemiologist with the Kaiser Permanente Northern California Division of Research in Oakland.
"These findings indicate that electromagnetic fields, from microwave ovens to countless wireless devices, may be contributing to childhood obesity risk. This finding could have implications for possibly reducing childhood obesity and better understanding the obesity epidemic. Like any scientific discoveries, the results need to be replicated by other studies."
For the study, researchers tracked the magnetic field exposures to more than 700 pregnant women in Kaiser Permanente's Northern California region. The women were asked to carry a meter measuring magnetic field levels during their pregnancies and their children were followed up to 13 years.
Researchers found children with the highest levels of in-utero magnetic field had the greatest risk of obesity or being overweight. The findings are the first to link increasing exposure to environmental magnetic fields, especially in-utero exposure, according to the scientists.
Previous research has linked electromagnetic fields to pregnancy outcomes, childhood diseases including asthma, and diabetes, Li said.
"Expectant mothers should take this new research into account, but they should not panic," said Dr. Ruth Shaber, medical director of the Center for Healthcare Delivery at the Kaiser Permanente Care Management Institute. "We still have a lot more to learn about the impact of the environment on pregnancy and young children."