Collaborative ECHO research led by Drew Day, PhD of Seattle Children’s Research Institute uses machine learning statistical algorithms to explore patterns of health outcomes in children. The researchers also investigated how exposures during pregnancy to phthalates—chemicals widely used in plastics that have previously been linked with preterm birth—can influence the development of multiple health conditions during childhood. This research, titled “Subpopulations of children with multiple chronic health outcomes in relation to chemical exposures in the ECHO-PATHWAYS consortium,” is published in Environment International.

Chronic health conditions, such as asthma and obesity, can develop together during childhood but are usually studied separately. The goal of this study was to use data from ECHO Cohort research sites across six U.S. cities to characterize “clusters,” or patterns, of obesity-related, lung health, and brain development outcomes in children and to investigate how these patterns relate to mothers’ exposures to phthalates during pregnancy.

ECHO researchers looked at 15 health outcomes in 1,092 children between the ages of 4 and 9 across six U.S. cities and collected measurements of phthalate exposure during pregnancy from 856 of these children’s mothers. Outcomes collected during this study included body mass index (BMI), IQ, anxiety, depression, irritability, learning disabilities, speech problems, asthma, wheeze, and nasal allergies. The researchers evaluated how children developed multiple outcomes and investigated how the probability of being in a particular group was affected by exposure to 15 plastic-associated phthalate chemicals during pregnancy. The researchers measured phthalate exposure during pregnancy using urine samples collected from 2007–2014 from mothers during late pregnancy.

The researchers identified three groups of children with a pattern of health outcomes that occurred together:

1. A group of relatively healthy children;
2. A group of children with lower IQs, elevated obesity, and slightly elevated asthma-related outcomes such as asthma, wheezing, and allergies; and
3. Another group of children with high asthma-related outcomes along with elevated obesity and some increase in anxiety- and depression-related outcomes.

Compared to children in the healthy group, other groups had more male children, mothers with higher BMI and lower education attainment, and lower household incomes. The researchers found that children—particularly boys—were more likely to be in the third group if their mothers were exposed to phthalates during pregnancy.

These findings suggest that exposure to phthalates during pregnancy might be associated with an increased risk of developing not only asthma and related lung outcomes, but also obesity and mental health issues such as anxiety and depression. This study also suggests that low-income households are at higher risk for worse childhood health outcomes.

“The three patterns of health outcomes seen in this study reveal more about how pediatric diseases might arise together,” said Dr. Day. “The insights from this study could help inform future research on what biological processes contribute to these health outcome patterns as well as better treatments and interventions to enhance child health.”

This study’s multi-outcome approach can be used in future studies to identify public health risks that may affect central biological processes that result in multiple negative health outcomes. ECHO Cohort researchers are working to extend this method to include several additional U.S. research sites, which will allow them to evaluate whether similar patterns are observed in a larger dataset. Larger studies will also help researchers characterize how demographic differences like income and sex may influence the development of multiple health outcomes during childhood.

Read the research summary.