[3] Toxic abortion chemicals studied at that time were: Petrochemicals, Heavy metals, Organic solvents, Tetrachloroethylene, Glycol ethers, 2-Bromopropane, Ethylene oxide, Anesthetic gases, and Antineoplastic drugs.
In 1932, the Journal of State Medicine reported on a natural variation, with the occurrence of "a considerable number of cases of toxic abortion" being caused by untreated dental caries.
[6] Newsweek magazine reported in May 2014 that a spike in stillborn babies in the town of Vernal, in Utah, had correlated with an increase in pollution from new gas and oil drilling.
"[7] Newsweek quoted one expert's observation that "We know that pregnant women who breathe more air pollution have much higher rates of virtually every adverse pregnancy outcome that exists.
"[7] A study published in the Journal of Environmental Health in October 2014 found tetrachloroethylene or PCE, to be "linked to increased risk for stillbirths and other pregnancy complications.