Maternal Occupational Exposure To Extremely Low Frequency Magnetic Fields And Electrical Shocks And Birth Outcomes Across Europe

Abstract

Background: Previous epidemiological studies have assessed adverse reproductive effects from maternal exposure to extremely low frequency magnetic fields (ELF-MF) exposure showing inconsistent results. The aim of this study is to assess the association between maternal occupational exposure to ELF-MF and electrical shocks during pregnancy and birth outcomes across Europe. Methods: We used a pooled dataset of 186,433 mother-child pairs enrolled in 12 birth cohorts throughout Europe. Occupational exposure to ELF-MF and electrical shocks was estimated based on individual data on information on the mother's occupation during pregnancy and linkage with job exposure matrices. Outcomes assessed included birthweight, gestational age, preterm birth, term low birthweight, small for gestational age, and infant sex ratio. Analyses were adjusted for several potentially confounding variables. We performed meta-analyses of cohort-specific estimates and explored heterogeneity. Results: Twenty two percent of women were exposed to medium levels of ELF-MF during pregnancy and 0.4% to high levels, whereas 5.9% of women were exposed to a medium risk of electrical shocks and 0.7% to a high risk. Exposure to high levels of ELF-MF during pregnancy was associated with a higher risk of term low birthweight (OR 1.99, 95%CI 1.00;3.99) compared to low levels of ELF-MF. Exposure to high risk of electrical shocks during pregnancy had a longer gestational length of 0.91 days (95%CI 0.07;1.68) compared to low risk of electrical shocks. Associations were consistent across cohorts with little heterogeneity. No associations were found with the other birth outcomes. Results were similar when both exposures were assessed together. Conclusions: This large study suggests that exposure to high levels of ELF-MF during pregnancy might be associated with impaired fetal growth at birth, whereas exposure to high risk of electrical shocks during pregnancy seems to be associated with longer gestational age.