Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. 
Clinical Pharmacist and Master’s student in Clinical Pharmacy with research interests in pharmacovigilance, behavioral interventions in mental health, and AI applications in clinical decision support. Experience includes digital health research with Bloomsbury Health (London) and pharmacovigilance practice in patient support programs. Published work covers drug awareness among healthcare providers, postpartum depression management, and patient safety reporting. What was studied?
This original research article examined the effects of prenatal exposure to three major heavy metals, lead, cadmium, and mercury on birth outcomes among Korean infants. Researchers conducted the study as part of the large-scale Korean Children’s Environmental Health (Ko-CHENS) study, spanning data collected from 2015 to 2019. The primary objective was to assess the association between maternal and cord blood concentrations of these heavy metals for example prenatal cadmium exposure at various pregnancy stages (early, late, and at birth) and key birth outcomes, specifically birth weight, small for gestational age (SGA), and large for gestational age (LGA).
The study used robust statistical methods, including linear and logistic regression models, and controlled for a comprehensive set of confounders such as maternal demographics, socioeconomic status, lifestyle behaviors, and pregnancy complications. This research is particularly relevant for heavy metal certification programs, as it evaluates even low-level exposures and their measurable impacts on critical early-life health parameters.
Who was studied?
The study population comprised 5,215 pregnant women recruited between 2015 and 2019 from the Ko-CHENS cohort, ultimately including 4,948 women with early pregnancy blood samples, 4,745 with late pregnancy samples, and 3,982 with cord blood samples after applying exclusion criteria (e.g., multiple or abnormal births, toxemia, missing data). The study consisted of women over 30 years old (over 95% in all groups), with most having a normal pre-pregnancy BMI and a high educational attainment. Lifestyle factors such as smoking and drinking were rare among participants. The research team extracted birth outcome data, including birth weight and gestational age classifications, from medical records and classified infants according to the international growth charts. The large and well-characterized sample enhances the generalizability of the findings within the Korean context and provides a strong foundation for regulatory consideration.
Most important findings
The key findings relate primarily to the effects of cadmium, with significant implications for regulatory standards. Researchers observed the maternal cadmium concentrations in both early and late pregnancy were significantly associated with lower birth weights (e.g., early pregnancy: β = −39.96 g per log-unit increase, 95% CI: −63.76, −16.17; late pregnancy: β = −37.24, 95% CI: −61.63, −12.84), even at concentrations lower than those reported in several other countries.
Notably, lead and mercury exposure showed less consistent associations with birth outcomes; late pregnancy lead was marginally associated with lower birth weight, while cord blood lead and mercury had positive associations with LGA, but not with SGA or low birth weight. Across all models, the findings underscore that cadmium is the most critical heavy metal regarding negative impacts on birth weight, supporting the hypothesis that even low-level prenatal cadmium exposure is detrimental to fetal growth.
Key implications
Based on compelling evidence, this research compels heavy metal certification programs, including HMTC, to establish conservative limits on cadmium exposure, with special emphasis on products intended for pregnant women. The study demonstrates that adverse effects on birth weight occur at cadmium levels lower than those currently observed in many populations, reinforcing the need for stringent safety standards and continuous monitoring. The lack of consistent associations for lead and mercury at the observed exposure levels also suggests that prioritizing cadmium in certification schemes could result in the greatest health benefit for fetal development. Additionally, the findings highlight the importance of considering cumulative and low-level exposures, as well as the need for ongoing public health measures and industry accountability to minimize prenatal cadmium exposure.
Citation
Shaffi Zinia S, Yang KH, Lee EJ, Lim MN, Kim J, Kim WJ, Ko-CHENS Study group. Effects of heavy metal exposure during pregnancy on birth outcomes. Sci Rep. 2023;13:18990. doi:10.1038/s41598-023-46271-0
Heavy metals are high-density elements that accumulate in the body and environment, disrupting biological processes. Lead, cadmium, arsenic, mercury, nickel, tin, aluminum, and chromium are of greatest concern due to persistence, bioaccumulation, and health risks, making them central to the HMTC program’s safety standards.
Lead is a neurotoxic heavy metal with no safe exposure level. It contaminates food, consumer goods and drinking water, causing cognitive deficits, birth defects and cardiovascular disease. HMTC’s rigorous lead testing applies ALARA principles to protect infants and consumers and to prepare brands for tightening regulations.
