Exposure to the toxic metal cadmium during pregnancy can have negative effects on fetal development, as researchers at the Rutgers School of Public Health have discovered. They believe that cadmium disrupts placental hormones, which play a role in regulating pregnancy physiology.
Unlike other toxins, cadmium does not directly impact the fetus by crossing the placenta. Instead, it is concentrated in the placenta tissue at rates of up to six times higher than in umbilical cord serum.
Zorimar Rivera-Núñez, an assistant professor in the Department of Biostatistics and Epidemiology and the lead author of the study published in the journal Toxics, explained, “We already know a lot about cadmium and its negative effects on fetal health, such as low birthweight. What we are still trying to understand is how the placenta regulates exposure to cadmium and other toxins.”
According to the researchers, very few epidemiological studies have examined the endocrine-disrupting potential of cadmium during pregnancy. To address this gap in knowledge, Rivera-Núñez, Megan Hansel (a doctoral degree student at the Rutgers School of Public Health), and Camila Capurro (a clinical research assistant and MPH student at the school) analyzed urine samples from 294 pregnant women who participated in the Understanding Pregnancy Signals and Infant Development (UPSIDE) study in Rochester, N.Y.
The study participants provided urine samples during each trimester and provided information about demographics, lifestyle, health history, and other factors.
By testing the urine samples for cadmium and sex steroid levels, including testosterone (which is crucial for fetal brain development), the researchers found that as cadmium levels increased, levels of free testosterone (testosterone not attached to a protein) decreased.
Meanwhile, total testosterone (both free and bound testosterone) remained stable, suggesting that cadmium may affect fetal exposure to sex steroids, which can have negative effects on fetal growth.
“We believe that cadmium is altering the process of testosterone binding during pregnancy,” explained Rivera-Núñez. “If cadmium interferes with these binding proteins, it could explain why we observe lower levels of free, or unbound, testosterone.”
Rivera-Núñez stated that one aim of this research is to help pregnant women avoid cadmium exposure. This will be challenging, as exposure occurs through tobacco products and is frequently found in foods due to industrial emissions, mining, and coal burning. Expectant mothers need to understand the risks, and regulators must work to prevent the toxin from entering the environment in the first place.
“If we can understand how cadmium affects growth in the womb, we may also gain insights into how similar chemicals impact the placenta,” Rivera-Núñez added. “Ultimately, this knowledge could help reduce exposure risks overall.”