Mercury and Prenatal Growth: A Systematic Review

Area of Science:

• Environmental Health
• Reproductive Toxicology
• Developmental Pediatrics

Background:

• The intrauterine environment is crucial for fetal development and long-term health.
• Mercury is a toxic metal that readily crosses the placenta, potentially disrupting fetal cellular processes.
• Existing observational studies on mercury exposure and prenatal growth lack comprehensive synthesis.

Purpose of the Study:

• To systematically review and synthesize evidence on the association between prenatal mercury exposure and key indicators of fetal growth.
• To assess the quality of existing studies investigating mercury's impact on birth weight, length, and head circumference.

Main Methods:

• A systematic literature search was conducted across Embase, MEDLINE/PubMed, PsycINFO, and Scopus.
• Twenty-seven studies from 17 countries examining mercury biomarkers and prenatal growth outcomes were included.
• Study quality was evaluated using the NIH Quality Assessment Tool, and findings were narratively synthesized.

Main Results:

• While some studies, particularly those with high mercury exposure or high quality, suggested a negative association between mercury and birth weight, overall results were inconsistent.
• Most included studies found no strong evidence linking prenatal mercury exposure to reduced birth length or head circumference.
• The review identified limited strong evidence for mercury-induced impairment of overall prenatal growth.

Conclusions:

• Current evidence does not strongly support a link between prenatal mercury exposure and impaired fetal growth, though a potential negative impact on birth weight warrants further investigation.
• The inconsistency in findings highlights the need for high-quality research with standardized methodologies to clarify mercury's role in prenatal development.
• Further research should focus on specific exposure levels, vulnerable populations, and robust study designs to elucidate mercury's effects on fetal growth parameters.