Prenatal exposure to higher magnetic field levels was associated with an increased risk for obesity in children, data showed.
“Pregnant women should avoid unnecessary exposure to magnetic fields, such as appliances, wireless devices, etc.,” study researcher De-Kun Li, MD, PhD, MPH, told Healio.com.
Li, of the Kaiser Permanente Division of Research, and colleagues wrote that poor diet and sedentary life cannot entirely explain the increase in obesity across numerous countries with varying dietary patterns and degrees of physical activity.
“Other environmental factors should be seriously examined, especially in pregnancy, that may damage the formation and development of fetal endocrine and metabolic systems, predisposing offspring to a higher risk of developing obesity or becoming overweight,” they wrote.
Li and colleagues conducted a prospective study by following 733 children whose mothers carried meters measuring magnetic field (MF) levels during pregnancy. Children were followed up to 13 years of age, and their medical charts were reviewed to obtain information on weight and height from birth. On average, 33 weight measurements per child were collected during the follow-up period to record information on growth patterns.
Results showed that prenatal exposure to medium to high (>1.5 milligauss) MF levels was associated with a 69% increased risk of being obese or overweight during childhood, compared with those exposed to low (≤1.5 milligauss) MF levels (OR=1.69; 95% CI, 1.01-2.84). The association revealed a dose-response relationship, with a 50% increased risk of obesity and overweight for medium (1.5 to 2.5 milligauss) in-utero exposure and a 84% increased risk for high exposure (>2.5 milligauss). Even after controlling for maternal parity, preexisting or gestational diabetes, family income, preterm delivery and childhood behaviors, the results did not change, according to the researchers. Among those who exhibited obesity persistently throughout the follow-up period, there was an almost five-fold increased risk associated with in-utero MF exposure (OR=4.97; 95% CI, 1.01-24.5). The association was not significant for those with transitory, or unlikely, obesity.
Among those children for whom the researchers had a complete follow-up from birth to the end of the study, there was a stronger association between MF exposure and obesity (OR=2.37; 95% CI, 1.13-5.00). There was also a stronger dose-response relationship among this group, with 1.85 times the risk for childhood obesity for medium MF levels and 2.80 times the risk for high MF levels.
Li and colleagues also observed a statistically significant interaction between the MF effect and maternal high BMI and pre-existing or gestational diabetes, two known risk factors for childhood obesity and overweight. The association between in-utero MF exposure and childhood obesity was much stronger in the presence of these risk factors.
“Given the worldwide epidemic of childhood obesity and ubiquitous MF exposure, this finding, if confirmed by other studies, could have implications for possibly reducing childhood obesity and understanding the obesity epidemic,” the researchers wrote.
Disclosure: The researchers report no relevant financial disclosures.