Microwave ovens and other appliances may be increasing the odds that your child will be overweight or obese later, new study said.

According to researchers, magnetic fields from these appliances during pregnancy can increase risk of the baby growing up to be overweight or obese by almost 69 percent.

"Pregnancy is a critical developmental stage that is among the most vulnerable periods to environmental exposures. These findings indicate that electromagnetic fields, from microwave ovens to countless wireless devices, may be contributing to childhood obesity risk," said De-Kun Li, a perinatal epidemiologist with the Kaiser Permanente Northern California Division of Research in Oakland, Calif., and the lead author of the study.

Mothers participating in the study carried a meter that measured the magnetic field that they were being exposed to during the pregnancy. The researchers then studied growth of some 733 babies born to these mothers. Researchers tracked every child in the study group for almost 11 years. During this period, researchers collected height and weight measurements.

Researchers found that low to medium exposure to electromagnetic field (EMF) was associated with about 50 percent increase in obesity risk while a high EMF exposure lead to an increase in obesity rates by about 84 percent.

"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," Dr. Li said.

Researchers have earlier found a link between high exposure to magnetic field during pregnancy and asthma risk in children. According to researchers, environment factors are amplified during development of the baby in the womb and these factors affect many organ systems and some of these changes remain for a long time.                   

"EMF exposure during pregnancy could impact the fetal development, including endocrine and metabolic systems, predisposing offspring to higher risk of obesity," Dr. Li said.

Don't panic, researchers say.

"Expectant mothers should take this new research into account, but they should not panic. We still have a lot more to learn about the impact of the environment on pregnancy and young children," said Dr. Ruth Shaber, medical director of the Center for Healthcare Delivery at the Kaiser Permanente Care Management Institute.

The study is published in the journal Scientific Reports.