Prenatal exposure to common class of chemicals may be linked to postpartum depression: NIH study

Individuals exposed to elevated levels of certain hormone-disrupting compounds while pregnant may experience a greater risk of postpartum depression, a new study has found.

Scientists linked these increased odds to a specific class of environmental contaminants, known as phthalates — ubiquitous chemicals found in numerous personal care and plastic consumer products.

They published their findings, supported by the National Institute of Health’s Environmental Influences on Child Health Outcomes (ECHO) program, on Thursday in JAMA Psychiatry.

Postpartum depression impacts up to 20 percent of new mothers, making this the most common pregnancy complication to occur following delivery, the authors noted.

“Finding new ways to prevent postpartum depression is crucial because most of the known risk factors, like genetics and stressful life events, can’t be altered,” first author Melanie Jacobson, of New York University’s Grossman School of Medicine, said in a statement.

Jacobson and her ECHO colleagues — from a variety of institutions nationwide — therefore set out to identify factors that might be controllable.

They sought to examine how common chemicals such as phenols, phthalates and parabens might contribute to postpartum depression symptoms, alongside other influences like genetics and stress.

“Focusing on prenatal exposure to these types of chemicals represents a novel interventional target,” Jacobson said.

To do so, the scientists measured the concentrations of these chemicals in urine samples of 2,174 pregnant individuals who participated in five ECHO Cohort Study Sites.

All study participants had parabens and nearly all had phthalates in their urine samples, the authors noted. 

These same participants then completed depression assessments between two and 12 months following delivery, to evaluate whether they were experiencing postpartum depression.

The researchers harmonized the data to the depression scale included in the NIH’s Patient-Reported Measurement Information System (PROMIS) — a standardized measurement tool that seeks to allow greater comparability of studies that involve self-reporting of disorders.

Ultimately, the scientists identified an association between elevated levels of phthalates during pregnancy and the development of postpartum depression.

Those individuals who met the criteria for postpartum depression were more likely to be Hispanic and from an ECHO study site located in Puerto Rico.

They typically had attained less education and presented with substantially higher prenatal depression scores, according to the study.

While the authors said they believe that their research is the largest study to date examining the impacts of environmental contaminants on postpartum depression, they highlighted an urgency for future such assessments.

“Given the ubiquitous nature of phthalates in the environment, future studies are needed to confirm these observations,” the scientists concluded, noting the potentially crucial role of “exogenous,” or external, factors. 

“This work underscores the importance of considering pregnancy a critical window of exposure to exogenous agents for maternal health outcomes after delivery, including psychiatric conditions,” they added.