Environmental toxins associated with recurrent pregnancy loss.

Couples experiencing recurrent pregnancy loss are often concerned that toxins within the environment have contributed to their reproductive difficulty. Questions posed by these couples to their health care providers are difficult to answer because scientifically accurate information regarding the reproductive impact of potential environmental toxins and other teratogens is not readily available. Heavy metals such as lead and mercury, organic solvents, alcohol, and ionizing radiation are confirmed environmental teratogens, and exposure could contribute to pregnancy loss. Caffeine, cigarette smoking, and hyperthermia are suspected teratogens, and the teratogenic impact of pesticides remains unknown. The teratogenic potential of multiple other environmental factors has been studied and is reviewed. Before definitive conclusions can be drawn regarding the teratogenicity of environmental exposures, several clinical factors need to be addressed, including gestational age at the time of exposure, the amount of toxin reaching the conceptus, the duration of exposure, the impact of other factors or agents to which the mother or her conceptus is simultaneously exposed, and the physiological status of the mother and conceptus. In addition, in a given population, the interrelationship between frequency of exposures,frequency of effects, and recognizability of adverse outcomes, such as spontaneous abortion, should be considered.