Chapter 5 - The Effect of Heavy Metals on Preterm Mortality and Morbidity

Abstract

Prematurity is the leading cause of neonatal morbidity and mortality especially in low-income and middle-income countries. Nowadays, changes in lifestyle have led to the development of new risk factors for preterm birth and preterm mortality with the increase of industrial pollution and anthropogenic or natural combustion activities worldwide. Heavy metals increase oxidative stress, lipid peroxidation, and tumor necrosis factor-alpha, such as pro-inflammatory cytokines, and reduce paraoxonase 1 and antioxidant activity. Also, heavy metals may be modulated by gene polymorphisms associated with these activities; they induce biomethylation DNA. Heavy metals interfere with the conjugation of detoxification or catalyzing enzymes by binding to these enzymes, and interfere with the trace elements metabolism by altering their gastrointestinal absorption or urinary excretion. They affect fetal development and cause intrauterine growth retardation, spontaneous abortions, premature delivery, malformations, birth defects, learning and behavior deficits, and neonatal deaths or preterm morbidity. Also, the impacts of environmental exposures on pregnancy outcome or development may have no thresholds. Therefore, the approach is to keep environmental exposures for all individuals as low as possible.