Environmental Exposures and Adverse Pregnancy-Related Outcomes

It has been known that pregnant women are exposed to a number of environmental chemicals and studies have reported that these environmental chemicals are detected from pregnant women of various population. Environmental exposures such as air pollution, pesticides, solvents, heavy metals, and chemicals including persistent organic pollutants (POPs) have implicated in adverse pregnancy-related outcomes. In addition to these environmental chemicals, phthalates and bisphenol A (BPA) are known as ubiquitous environmental chemicals and their endocrine disrupting effects have been reported from animal studies. These chemicals can impact the ability to become pregnant and sustain a healthy pregnancy. Taking trend of environmental chemical levels over the years into consideration is of cardinal importance for investigating adverse birth outcomes because oftentimes associations can be found at high exposure levels such as accidental or occupational settings. From individual studies and meta-analysis, systematic reviews of recent years, evidences on outdoor air pollution during pregnancy, and adverse birth outcomes have been strengthened. Especially, fairly good evidence for maternal exposure to PM2.5 pollution during pregnancy is associated with increased risk of adverse birth outcomes. Heavy metal exposures and PFOA exposure during pregnancy may moderately be associated with adverse birth outcomes; however, not sufficient investigation has been conducted for substitutions for PFOS and PFOA. Besides, it is important to consider concentrations of PFAS in association with adverse birth outcomes as PFOS concentration is decreasing since the Stockholm convention. Inconsistent findings have been reported for phthalates and BPA exposure during pregnancy and birth outcomes. Some of the studies mentioned different influence between male and female infants or sex-specific of environmental exposure on birth outcomes. Studies on genomic analysis, transcriptome analysis, proteome analysis, and epigenome analysis should be accelerated to elucidate mechanisms of observed results from epidemiological studies.