Prenatal Magnetic Field Exposure Ups Children's Asthma Risk

Dose-response relationship observed for magnetic field exposure level and asthma risk

WEDNESDAY, Aug. 3 (HealthDay News) -- Maternal exposure to high levels of magnetic fields (MFs) during pregnancy is associated with increased asthma risk in the offspring, according to a study published online Aug. 1 in the Archives of Pediatrics & Adolescent Medicine.

De-Kun Li, M.D., Ph.D., from Kaiser Permanente in Oakland, Calif., and colleagues investigated the association between maternal exposure to MFs during pregnancy and asthma risk in offspring. Data for MF levels were collected through meter readings during pregnancy, and 626 children diagnosed with asthma were followed up for up to 13 years.

The investigators found a statistically significant linear dose-response relationship between increasing maternal median daily MF prenatal exposure and an increased risk of asthma in the offspring, after adjusting for potential confounders. Every 1 milligauss (mG) increase in maternal MF exposure levels correlated to a 15 percent increased asthma rate in the offspring (hazard ratio [HR], 1.15). Compared to children whose mothers had low MF exposure levels (median 24-hour level ≤0.3 mG), children whose mothers had a medium MF level exposure (>0.3-2.0 mG) had a 74 percent increased asthma rate (adjusted HR, 1.74), and children whose mothers had a higher exposure (>2.0 mG) had a 3.5-fold increased asthma rate (adjusted HR, 3.52). A statistically significant synergistic correlation between MF effect and maternal history of asthma and birth order was observed.

"A high maternal MF exposure level in pregnancy is associated with a significantly increased risk of asthma in offspring," the authors write.

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