Savitz David A, Herring Amy H, Mezei Gabor, Evenson Kelly R, Terry James W, Kavet Robert
Department of Epidemiology School of Public Health, and Carolina Population Center, University of North Carolina, Chapel Hill, USA.
Epidemiology. 2006 Mar;17(2):222-5. doi: 10.1097/01.ede.0000197294.05564.08.
Peak magnetic field exposure was associated with increased risk of miscarriage in 2 recent studies. Reduced physical activity levels in healthy pregnancies may affect measured exposure and thus bias results.
We recruited 100 pregnant women to wear an Actigraph accelerometer and EMDEX magnetic field monitor for a 7-day period. We evaluated the association between physical activity and magnetic field exposure (peaks and time-weighted average) using generalized estimating equations and linear mixed models.
We found a positive association between level of activity and likelihood of incurring elevated exposure in the person-day analysis, most strongly for cutpoints of 16 or 20 mG, for both working and nonworking women among whom odds ratios in the uppermost quartile ranged from 2.1 to 2.6. A positive association was found using person-minutes only among nonworking women.
Physical activity may affect peak magnetic field exposure. If the early nausea and later cumbersomeness of healthy pregnancies leads to reduced physical activity, this could distort measured magnetic field-health outcome associations.
在最近的两项研究中，峰值磁场暴露与流产风险增加有关。健康孕期体力活动水平降低可能会影响测量的暴露量，从而导致结果出现偏差。
我们招募了100名孕妇，让她们佩戴活动记录仪加速度计和电磁环境探测器磁场监测仪，为期7天。我们使用广义估计方程和线性混合模型评估体力活动与磁场暴露（峰值和时间加权平均值）之间的关联。
在人日分析中，我们发现活动水平与暴露量升高的可能性之间存在正相关，对于16或20毫高斯的切点最为明显，在职和非在职女性中，最高四分位数的比值比在2.1至2.6之间。仅在非在职女性中，使用人分钟数时发现了正相关。
体力活动可能会影响峰值磁场暴露。如果健康孕期早期的恶心和后期的行动不便导致体力活动减少，这可能会扭曲测量的磁场与健康结果之间的关联。
