Exposure to metals may disrupt pregnant women's hormones and boost the odds of complications such as preeclampsia, preterm birth, and low birth weight, according to a new study.
Metals such as nickel, arsenic, cobalt, and lead have been associated with pregnancy complications, but it's been unclear why.
"A delicate hormonal balance orchestrates pregnancy from conception to delivery and perturbations of this balance may negatively impact both mother and fetus," said lead author Zorimar Rivera-Núñez, assistant research professor in the School of Public Health at Rutgers University in Piscataway, N.J.
For this study, the researchers analyzed blood and urine samples from 815 women in Puerto Rico. They were enrolled in a long-term study of environmental exposures in pregnant women and their children.
The new research found that some metals may disrupt the endocrine system, which regulates hormones. These disruptions may increase children's health and disease risk at birth and later in life.
For example, disruptions in sex-steroid hormones during pregnancy have been linked to inadequate fetal growth, which leads to low birth weight. Birth weight is strongly associated with a child's risk for chronic diseases, including obesity and breast cancer.
The disruption to the endocrine system may depend on when in the pregnancy the mother was exposed to the metals, according to the researchers.
Pregnant women in Puerto Rico have higher metal exposure than in those in the continental United States.
"Puerto Rico has one of the highest rates of Superfund sites of any of the U.S. jurisdictions with 18 active sites, which can contribute to the higher rates of exposure to toxic metals," Rivera-Núñez said in a Rutgers news release.
Women in Puerto Rico have significantly higher rates of preterm birth at nearly 12% (compared to the rest of the United States at under 10%), and other adverse birth outcomes, Rivera-Núñez said.
"Additionally, exposure to environmental pollution is exacerbated by extreme weather events such as hurricanes, droughts, and flooding, which may result in elevated exposures to Superfund sites," she added.
The findings were published recently in the journal Environment International.
More research is needed to learn about the long-term effects of metal exposure during pregnancy, the researchers concluded.