Extremely low frequency magnetic fields and fertility: a follow up study of couples planning first pregnancies

Objectives-To evaluate the impact of extremely low frequency (ELF) magnetic fields on markers of human fertility. Methods-A follow up study of time to pregnancy, semen quality, and reproduc tive hormones was conducted among couples planning first pregnancies (36 ma les were welders and 21 were non-welders). The male and the female partner were monitored for exposure to ELF magnetic field by personal exposure mete rs. As summary measures of exposure the median value was calculated togethe r with the 75 percentile value and the proportion of measurements exceeding 0.2 and 1.0 mu T, respectively. Each summary measure was divided in three categories: low, medium, and high. Results-Couples in which the man had a medium or a high proportion of measu rements >1.0 mu T had a reduced probability of conception per menstrual cyc le compared with the men with low exposure, but the result was only signifi cant for the men with medium exposure. This finding was partly attributable to a high probability of conception per menstrual cycle among the men with low exposure compared with non-welders in the original cohort of 430 coupl es. Other summary measures were not related to probability of conception or other markers of fertility. A possible negative association was found betw een high probability of conception and female exposure measures based on th e median, the 75 percentile, and the proportion of measurements >0.2 mu T, but no association was found with the proportion of measurements >1.0 mu T. Conclusions-The findings provide no consistent support for a hypothesis of a deleterious effect of low level ELF magnetic fields on markers of human f ertility. However, due to the relatively small size of the studied populati on only large associations would be detected.