251. Physical activity and magnetic field exposure in pregnancy.
- Author
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Savitz DA, Herring AH, Mezei G, Evenson KR, Terry JW Jr, and Kavet R
- Subjects
- Adult, Bias, Female, Gestational Age, Humans, Linear Models, Monitoring, Ambulatory instrumentation, North Carolina, Pregnancy, Risk Factors, Electromagnetic Fields, Motor Activity
- Abstract
Background: 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., Methods: 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., Results: 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., Conclusion: 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.
- Published
- 2006
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