Exposure to electromagnetic fields during pregnancy with emphasis on electrically heated beds: association with birthweight and intrauterine growth retardation.

Abstract

Several animal and human studies indicate that fetal growth may be retarded following exposure to electromagnetic fields (EMF). We conducted a prospective study (N = 2,967) to evaluate the relation of birthweight and fetal growth retardation with use of electrically heated beds (electric blankets and heated water beds) during pregnancy. A "nested" study design allowed monitoring of exposure at different stages of pregnancy using both direct and indirect methods. We assessed EMF exposure using personal monitors, home measurement, video display terminal use, and wire code. Exposure to EMF during pregnancy, either at conception, at < or = 16 weeks, or in the third trimester, showed no important relation to risk of low birth-weight or fetal growth retardation. This result was the same whether we used subjective measures of exposure or direct measurement. Use of video display terminals at home or work, exposure to > or = 2.0-milligauss fields as measured by home or personal monitors, and home wire code were unrelated to the reproductive outcomes studied. A time-weighted analysis of electric bed use, which accounted for strength of EMF exposure and hours of use, also showed evidence of no meaningful increase in risk. None of the exposure measures showed a dose response relation to risk. We conclude that risk of low birth-weight and intrauterine growth retardation is not increased after electrically heated bed use during pregnancy.

AI evidence extraction

Main findings

In this prospective study of 2,967 pregnancies, EMF exposure during pregnancy (including electrically heated bed use) showed no important relation to low birth-weight or fetal growth retardation across multiple exposure windows. Results were consistent across subjective exposure measures and direct measurements (personal monitors, home measurements), and no dose-response relationship was observed.

Outcomes measured

• birthweight
• low birth-weight
• fetal growth retardation
• intrauterine growth retardation

Limitations

• Specific EMF frequencies and detailed exposure metrics beyond milligauss thresholds were not provided in the abstract.
• Outcome and exposure assessment details (e.g., confounder adjustment, statistical estimates) are not described in the abstract.

Suggested hubs

• occupational-exposure (0.28)
  Includes assessment of video display terminal use at work as an exposure source during pregnancy.

{
    "study_type": "cohort",
    "exposure": {
        "band": "ELF",
        "source": "electrically heated beds (electric blankets, heated water beds); also video display terminals; residential wiring (wire code)",
        "frequency_mhz": null,
        "sar_wkg": null,
        "duration": "during pregnancy (at conception, ≤16 weeks, third trimester); time-weighted analysis included hours of use"
    },
    "population": "Pregnant individuals (prospective study during pregnancy)",
    "sample_size": 2967,
    "outcomes": [
        "birthweight",
        "low birth-weight",
        "fetal growth retardation",
        "intrauterine growth retardation"
    ],
    "main_findings": "In this prospective study of 2,967 pregnancies, EMF exposure during pregnancy (including electrically heated bed use) showed no important relation to low birth-weight or fetal growth retardation across multiple exposure windows. Results were consistent across subjective exposure measures and direct measurements (personal monitors, home measurements), and no dose-response relationship was observed.",
    "effect_direction": "no_effect",
    "limitations": [
        "Specific EMF frequencies and detailed exposure metrics beyond milligauss thresholds were not provided in the abstract.",
        "Outcome and exposure assessment details (e.g., confounder adjustment, statistical estimates) are not described in the abstract."
    ],
    "evidence_strength": "moderate",
    "confidence": 0.7800000000000000266453525910037569701671600341796875,
    "peer_reviewed_likely": "yes",
    "keywords": [
        "pregnancy",
        "electromagnetic fields",
        "ELF",
        "electric blankets",
        "heated water beds",
        "electrically heated beds",
        "birthweight",
        "low birth-weight",
        "intrauterine growth retardation",
        "fetal growth retardation",
        "personal monitors",
        "home measurement",
        "video display terminals",
        "wire code"
    ],
    "suggested_hubs": [
        {
            "slug": "occupational-exposure",
            "weight": 0.2800000000000000266453525910037569701671600341796875,
            "reason": "Includes assessment of video display terminal use at work as an exposure source during pregnancy."
        }
    ]
}

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