Stillbirth and residential proximity to extremely low frequency power transmission lines: a retrospective cohort study

Objectives The relationship between electromagnetic field exposure and stillbirth has not been evaluated. We assessed associations between residential proximity to extremely low frequency power transmission lines and stillbirth across gestational age. Methods Data included singleton live births (N=514 826) and stillbirths (N=2033) for 1998-2007 in metropolitan areas of Quebec, Canada. Using power transmission line maps, the distances between lines and residential six-digit postal codes (<25, 25-49.9, 50-74.9, 75-99.9, >= 100 m) were calculated. Generalised estimating equations were used to compute ORs and 95% CIs for distance and stillbirth, accounting for individual and area characteristics. Early preterm (<28 weeks), late preterm (28-36 weeks) and term (>= 37 weeks) stillbirths were examined relative to fetuses-at-risk. Results There was no association between distance and preterm stillbirth. The odds of term stillbirth for <25 m were greater compared to >= 100 m (OR 2.25, 95% CI 1.14 to 4.45), but no dose-response pattern was apparent. Conclusions A graded dose-response trend between distance to lines and odds of stillbirth was not found, but the likelihood of term stillbirth was elevated for residences within 25 m of power transmission lines. Residential proximity to transmission lines is unlikely to be associated with stillbirth, but more research is needed to rule out a possible link.