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Miscarriages among female physical therapists who report using radio- and microwave-frequency electromagnetic radiation.

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Ouellet-Hellstrom R, Stewart WF · 1993

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Physical therapists using microwave diathermy equipment had up to 59% higher miscarriage rates, suggesting pregnancy vulnerability to microwave radiation exposure.

Plain English Summary

Summary written for general audiences

Researchers surveyed over 42,000 physical therapists to examine whether occupational exposure to microwave diathermy equipment affected pregnancy outcomes. They found that women who used microwave diathermy units during the six months before conception or during the first trimester had a 28% higher risk of miscarriage, with risk increasing to 59% for those with the highest exposure levels (20 or more uses per month). Interestingly, shortwave diathermy equipment showed no increased risk.

Why This Matters

This 1993 study provides important evidence that microwave radiation exposure during critical periods of pregnancy can affect fetal development. The dose-response relationship - where higher exposure levels correlated with higher miscarriage rates - strengthens the biological plausibility of these findings. What makes this research particularly relevant today is that the microwave frequencies used in diathermy equipment overlap with those used in modern wireless devices, though at much higher power levels. The science demonstrates that timing of exposure matters critically, with the period around conception and early pregnancy showing particular vulnerability. This adds to a growing body of evidence suggesting that pregnant women should minimize EMF exposure during these sensitive developmental windows.

Exposure Information

Specific exposure levels were not quantified in this study.

Study Details

Recent studies suggest that use of shortwave diathermy is associated with an excess risk of birth defects, perinatal deaths, and late spontaneous abortions among the offspring of exposed female therapists. To assess the impact of occupational use of microwave and shortwave diathermy at the time of conception, the authors mailed questionnaires to 42,403 physical therapists in 1989.

Both occupational and reproductive histories were obtained. Exposures to shortwave and microwave dia...

Pregnancies of mothers reporting microwave use 6 months prior to the pregnancy or during the first t...

Cite This Study
Ouellet-Hellstrom R, Stewart WF (1993). Miscarriages among female physical therapists who report using radio- and microwave-frequency electromagnetic radiation. Am J Epidemiol 138(10):775-786, 1993.
Show BibTeX
@article{r_1993_miscarriages_among_female_physical_2493,
  author = {Ouellet-Hellstrom R and Stewart WF},
  title = {Miscarriages among female physical therapists who report using radio- and microwave-frequency electromagnetic radiation.},
  year = {1993},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/8237966/},
}
PubMed: 8237966

Cited By (117 papers)

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Quick Questions About This Study

Yes, a 1993 study of 42,000 physical therapists found microwave diathermy increased miscarriage risk by 28%. Women with the highest exposure (20+ uses monthly) had 59% higher risk. The risk increased with more frequent use during pregnancy or six months before conception.
Research suggests microwave diathermy therapy may increase miscarriage risk. Physical therapists who used microwave diathermy equipment during early pregnancy or before conception showed 28% higher miscarriage rates, with risk rising to 59% for frequent users in one major study.
Microwave diathermy equipment used in physical therapy may affect pregnancy outcomes. A study found 28% higher miscarriage risk among therapists using these devices, while shortwave diathermy showed no increased risk. The effect was strongest with frequent exposure.
Occupational microwave exposure from diathermy equipment increased miscarriage risk by 28% in one study. Risk climbed to 59% for women with highest exposure levels. However, this research focused specifically on medical equipment, not household microwave ovens.
Microwave radiation from medical diathermy equipment may impact early pregnancy by increasing miscarriage risk. Research found 28% higher miscarriage rates among exposed women, with effects most pronounced during the first trimester and six months before conception.