Research has previously shown that exposure to metals and a mother’s experience of psychosocial stress during pregnancy can both increase the odds of adverse birth outcomes, including preterm birth. But these studies looked at metals exposure and psychosocial stress independently. In a study recently published in Environment International, PROTECT Project 1 researchers conducted an analysis to see how maternal psychosocial stress modified the impacts of metals exposure on birth outcomes. The results suggest that poor psychosocial status during pregnancy may worsen the negative impacts of metals contamination on birth outcomes.

To measure the psychosocial status of study participants, researchers used the results from four questionnaires administered during pregnancy to assess a mother’s experience of depression, perceived stress, social support, and positive and negative life experiences during pregnancy. Researchers used a K-means clustering method to compile the scores of these four instruments and sort the participants into two clusters, representing “good” and “poor” psychosocial stress during pregnancy.

Metals analysis was completed on blood samples taken during the first and third trimesters. Researchers then looked at the impacts of metals on birth outcomes and compared the results between the “good” and “poor” psychosocial stress clusters. In the “poor” psychosocial stress group, the association between metals contamination and adverse birth outcomes was significantly stronger. “Specifically, women with ‘poor’ psychosocial status had stronger associations between the blood manganese concentration and shorter gestational age and higher risk of preterm birth,” lead author Pahriya Ashrap says. “The association between copper and small for gestational age was also statistically significant only among women having ‘poor’ psychosocial status.”

Interventions are needed to help reduce metals contamination, especially during pregnancy. However, these results suggest that interventions targeting a mother’s psychosocial stress may help decrease some of those risks.  

These findings also highlight the importance of interventions after major weather or environmental events that can lead to both increased exposure to harmful chemicals and to maternal stress, as Hurricane Maria did when it made landfall in Puerto Rico in 2017. “Environmental contamination conditions exacerbated by the flooding and the destruction of buildings doubled with the elevated levels of stress…created an especially vulnerable state for pregnant women,” Ashrap says. “Ultimately, the identification of modifiable psychosocial factors may lead to interventions during pregnancy to reduce the harmful effects of chemicals on birth outcomes.”