Heavy metals in miscarriages and stillbirths in developing nations

Objectives: Cases of miscarriage and stillbirths due to heavy metal poisoning continue to be on the rise in developing nations. In these countries like Nigeria, the menace of miscarriage is not readily linked to heavy metal exposure. This could be as a result of insufficient scientific data available due to poor documentation and inadequate public health education on the consequences of these heavy metals on maternal health. The heavy metals mercury, lead and cadmium are toxicants which have been shown to cross the placental barrier to accumulate in fetal tissues. Methods: For this review, relevant databases were searched for original scientific reports and a total of 100 articles were retained for analysis. Required data was extracted from these studies and their methodology assessed. Results: Miscarriages and stillbirths were observed from exposure to five heavy metals namely; mercury, arsenic, lead, chromium and cadmium. These heavy metals were associated with increased incidence of miscarriages in developing nations. In Nigeria, women with history of miscarriage had blood lead levels >25 µg/dL during pregnancy with approximately 41.61% increase in miscarriage incidence. Cadmium blood level was found to be 85.96 ± 1.09 μg/dl with a 9.50% increase in miscarriage incidence in women exposed to mercury in comparison to the unexposed group. For chromium, a 1.60% increase in the incidence of miscarriage in women exposed to chromium was reported. For cadmium and arsenic, 83.93% and 5.88% increase in incidence were reported respectively. Similar data were obtained for Jamaica (mercury = 7.29 ± 9.10 μg/l), Egypt (Cadmium = 1.17%; Lead = 32.33%). Conclusion: Medical practitioners and Toxicologists involved in women health in sub-Sahara Africa SSA should consider if these heavy metals can become additional biomarkers in the diagnosis of miscarriages and stillbirths.