Epidemiological study (observational study)

Residential exposure to 50 Hz magnetic fields and the association with miscarriage risk: a 2-year prospective cohort study epidem.

By: Wang Q, Cao Z, Qu Y, Peng X, Guo S, Chen L

Published in: PLoS One 2013; 8 (12): e82113

Aim of study (acc. to author)

A cohort study was conducted in China to investigate the association between residential exposure to 50 Hz magnetic fields and the miscarriage risk.

Endpoint/type of risk estimation

reproductive effects and pregnancy outcomes: miscarriage

Type of risk estimation:

incidence

(relative risk (RR))

Exposure

- 50/60 Hz
- magnetic field
- power transmission line
- electrical substation
- residential

Assessment

measurement: magnetic field strength measurements at the front door of the houses, in the alleys in front of the subjects' houses, and at public clubs for entertainment on days when the electric power supply loads were relatively high

Exposure groups

Group	Description
Reference group 1	unexposed, magnetic field strength: < 0.1 µT
Group 2	exposed, magnetic field strength: ≥ 0.1 µT
Group 3	group A, magnetic field strength: 0.1 - < 0.4µT
Group 4	group B, magnetic field strength: 0.4 µT - 4.26 µT

Population

Group:
- women
- children in utero
Characteristics: pregnant women from the Chinese Han population
Observation period: May 2010 - May 2012
Study location: China (2 towns in the Pearl-River Delta)
Exclusion criteria: pregnant women with a history of thalassemia, sicklemia, G-6-PD deficiency, thyrotoxicosis, diabetes; living in the area less than 6 months or migrating

Study size

Type	Value
Total	449
Evaluable	413

Other:

follow-up every 2 months

Statistical analysis method:

Cox proportional regressions analysis

(adjustment:

age
residential area
education
depression, smoking, history of abnormal pregnancy outcomes and diseases specific to women, X-ray, use of folic acid, alcohol

)

Results (acc. to author)

Of all 562 magnetic field strength measurements, 33.6% of the measurements were lower than 0.05 µT, 13.3% of the measurements were higher than 0.4 µT, and 4.6% of measurements were higher than 1.0 µT. The median was 0.099 µT.
No significantly increased risk of miscarriage in the exposed group was found to be associated with the average front-door exposure (RR 1.4; CI 0.6-3.1). However, miscarriage risk was found to be significantly associated with maximum alley exposure in the exposed group (RR 2.35, CI 1.18-4.71), after adjusting for confounders the hazard ratio was 1.72 (CI 1.10-2.69).
The authors concluded that the association between miscarriage risk and the exposure to magnetic fields was not confirmed in this study although the miscarriage incidence was shown to be positively associated with the maximum alley magnetic field exposure.

Study funded by

Public Sector Program of National Environmental Protection, China

de Souza S et al. (2021): High prevalence of gastroschisis in Brazilian triple side border: A socioenvironmental spatial analysis
Ingle ME et al. (2020): Association of personal exposure to power-frequency magnetic fields with pregnancy outcomes among women seeking fertility treatment in a longitudinal cohort study
Esmailzadeh S et al. (2019): Exposure to Electromagnetic Fields of High Voltage Overhead Power Lines and Female Infertility
Ren Y et al. (2019): Prenatal exposure to extremely low frequency magnetic field and its impact on fetal growth
Auger N et al. (2019): Maternal proximity to extremely low frequency electromagnetic fields and risk of birth defects
Li DK et al. (2017): Exposure to Magnetic Field Non-Ionizing Radiation and the Risk of Miscarriage: A Prospective Cohort Study
Su XJ et al. (2014): Correlation between exposure to magnetic fields and embryonic development in the first trimester
Tan TC et al. (2014): Lifestyle Risk Factors Associated with Threatened Miscarriage: A Case-Control Study
Shamsi Mahmoudabadi F et al. (2013): Exposure to extremely low frequency electromagnetic fields during pregnancy and the risk of spontaneous abortion: a case-control study
Auger N et al. (2012): Stillbirth and residential proximity to extremely low frequency power transmission lines: a retrospective cohort study
Malagoli C et al. (2012): Maternal exposure to magnetic fields from high-voltage power lines and the risk of birth defects
Lee GM et al. (2002): A nested case-control study of residential and personal magnetic field measures and miscarriages
Li DK et al. (2002): A population-based prospective cohort study of personal exposure to magnetic fields during pregnancy and the risk of miscarriage
Savitz DA et al. (1994): Residential magnetic fields, wire codes, and pregnancy outcome