Home Conditions and Outdoor Air Pollution May Together Influence Children’s Asthma Risk, ECHO Study Finds

Authors: Akihiro Shiroshita, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Childhood asthma may be influenced by multiple indoor and outdoor environmental exposures. Prior research has examined indoor and outdoor exposures separately and frequently lacked the power to fully evaluate their cumulative or interacting effects on childhood asthma. The ECHO Cohort allowed researchers to bring together data from many sites across the country, providing a clearer picture of how different environmental factors may influence childhood asthma.

What were the study results?

The study found that several environmental exposures during early childhood were linked to asthma risk. First, exposure to ambient fine particulate air pollution (PM_2.5) was associated with an increased risk of developing asthma. In addition, water damage or dampness in the home was also linked to a higher asthma risk, even after accounting for PM_2.5exposure, indicating an independent effect. In contrast, having a dog in the home during infancy was associated with a reduced risk of childhood asthma.

What was this study's impact?

The study demonstrated the importance of considering multiple early-life exposures together when assessing risk factors for childhood asthma. It highlighted that both indoor (home dampness, pets) and outdoor (PM_2.5) exposures should be considered in prevention strategies.

Who was involved?

Participants included 6,413 children born between 1987 and 2016, enrolled in nine ECHO Study Sites across the United States. These sites included both general-risk and high-risk populations at higher risk, defined by a parental history of asthma or allergy.

What happened during the study?

The study looked at children’s early-life environments to understand how they relate to asthma risk. Researchers examined levels of outdoor air pollution during the first three years of life, along with conditions inside the home, such as water damage or dampness, whether dogs or cats were present during infancy, and exposure to dust mites. Childhood asthma was identified based on reports from caregivers or a doctor’s diagnosis between birth and age five. The analysis considered differences in family and neighborhood factors that could also affect asthma risk, helping to isolate the role of these environmental exposures.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should not make changes to your health without first consulting your healthcare professional.

What happens next?

Additional studies examining how indoor and outdoor exposures interact could help researchers better understand their role in childhood asthma risk. Future research could also explore ways to reduce or prevent harmful exposures in early life.

Where can I learn more?

Access the full journal article, titled “Individual and combined effects of indoor home exposures and ambient PM_2.5during early life on childhood asthma in US birth cohort studies,” in Environmental Epidemiology.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published December 23, 2025

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Home Conditions and Outdoor Air Pollution May Together Influence Children’s Asthma Risk, ECHO Study Finds

ECHO Study Finds Association Between Exposure to Certain PFAS and Maternal Depression & Stress During/After Pregnancy

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ECHO Study Finds Association Between Exposure to Certain PFAS and Maternal Depression & Stress During/After Pregnancy

Authors: Susanna D. Mitro, Lyndsay Avalos, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Per- and polyfluoroalkyl substances (PFAS) are a large, complex group of synthetic chemicals found in some household products such as cookware and stain-resistant fabrics. These substances are often referred to as “forever chemicals” because they don’t break down easily, causing them to build up over time in water, soil, and air. Previous studies have shown that PFAS can negatively affect the brain, and there is conflicting evidence about their potential effects on depression and perceived stress during and after pregnancy. Depression and stress during these periods are common and linked to adverse health outcomes for both parents and children. This study aimed to clarify whether PFAS exposure during pregnancy is associated with an increased risk of depression and stress, and whether social factors affect these associations.

What were the study results?

Of the seven PFAS included in this study, some types were linked to changes in depression and stress for pregnant and postpartum participants. For example, higher levels of N-methyl perfluorooctane sulfonamido acetic acid (N-MeFOSAA) were associated with slightly higher depressive symptoms and perceived stress, especially postpartum, while higher perfluorodecanoic acid (PFDA) levels were associated with a lower risk of diagnosed depression and lower prenatal perceived stress. Exposure to perfluorooctanesolfonic acid (PFOS) showed a mixed pattern where moderate exposure was associated with increased depression risk, but the highest exposure was associated with lower depression risk.

When looking at all seven PFAS types as a group, there was generally no strong link to depression diagnosis or severity, but the data did show higher stress at low to moderate exposures, but lower stress as high exposure. The effects of PFAS were different depending on social factors. For example, people who were not born in the U.S. or who had higher social vulnerability sometimes showed stronger links between PFAS and depression or stress.

What was this study's impact?

Overall, the associations observed in this study were small, so more research is needed to fully understand the effects of PFAS on pregnancy mental health. This study adds to mounting evidence that PFAS exposure during pregnancy may have negative health effects during pregnancy, reinforcing the importance of minimizing exposure to PFAS during this sensitive time.

Who was involved?

The study included 4,403 pregnant participants from 16 ECHO Cohort study sites.

What happened during the study?

Researchers measured the levels of seven PFAS in the mother’s blood during pregnancy. Pregnant participants reported whether they received a diagnosis of depression during pregnancy and filled out surveys on their depression and stress symptoms before and after giving birth. The researchers then used statistical methods to evaluate potential associations between PFAS exposure and mental health outcomes and how social factors may have influenced these associations.

What happens next?

Future studies could help researchers clarify the biological mechanisms linking PFAS exposure to depression and stress and explore the role of social factors in influencing these associations.

Where can I learn more?

Access the full journal article, titled “Gestational PFAS concentrations in association with maternal depression and perceived stress during pregnancy and postpartum in the ECHO cohort,” in Environmental Research.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published December 1, 2025

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ECHO Study Finds Association Between Exposure to Certain PFAS and Maternal Depression & Stress During/After Pregnancy

Exposure to Fine Particulate Air Pollution in Early Pregnancy Linked to Lower Birth Weight, ECHO Study Finds

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Exposure to Fine Particulate Air Pollution in Early Pregnancy Linked to Lower Birth Weight, ECHO Study Finds

Authors: Whitney Cowell, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Babies born with low birth weight are at a higher risk for health problems both at birth and later in life. Prior research has shown that exposure to fine particulate matter (PM_2.5)—very small inhalable particles found in air pollution—during pregnancy can negatively affect birth weight. Many past studies examined average exposure over pregnancy, which may miss specific windows when the baby is most sensitive. The goal of this study was to identify the specific weeks in pregnancy when babies are most vulnerable to PM_2.5 exposure.

What were the study results?

Exposure to PM_2.5 during pregnancy was associated with lower birth weight for gestational age, particularly when exposure occurred in the early weeks of pregnancy (weeks 1–5). Male newborns appeared more sensitive to exposure than females. The study also found regional differences, with stronger associations observed in the Northeast, South, and Midwest. This may relate to differences in the types of particles found in the air in these regions.

What was this study's impact?

This study gives us a clearer picture of when during pregnancy air pollution may be most harmful to a baby’s growth. Understanding these sensitive time periods can inform future research on what’s happening in the body during those weeks and why pollution may have a bigger impact during those times.

Who was involved?

The study included 16,868 pregnant participants from the ECHO Cohort, spanning 50 sites across the United States.

What happened during the study?

Researchers applied computer models to estimate pregnant participants' weekly exposure to PM_2.5 throughout their pregnancies. Birth weight was recorded at the time of delivery and then standardized using national growth charts to account for variations in gestational age (length of pregnancy). Analysts used statistical methods to identify how overall and week-specific PM_2.5exposure related to birthweight. These methods also tested whether the impact of PM_2.5differed by the baby’s sex, race or ethnicity of the parents, or the region of the country the mother lived in during pregnancy.

What happens next?

Future studies could help explain how different types and sizes of pollution particles affect baby’s growth. Additional research could also help identify the periods of pregnancy when reducing exposure would have the greatest impact.

Where can I learn more?

Access the full journal article, titled “PM_2.5 in relation to birth weight: exploring windows of susceptibility in the ECHO Cohort,” in JAMA Network Open.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published December 1, 2025

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Exposure to Fine Particulate Air Pollution in Early Pregnancy Linked to Lower Birth Weight, ECHO Study Finds

Wildfire Smoke Exposure May Be Linked to Higher Risk of Preterm Birth, ECHO Study Finds

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Wildfire Smoke Exposure May Be Linked to Higher Risk of Preterm Birth, ECHO Study Finds

Authors: Allison Sherris, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Wildfire smoke exposure is a growing threat to public health in the United States. The fine particulate matter (PM_2.5) in wildfire smoke may be more harmful than other kinds of ambient air pollution because of the chemicals it’s made of and how these chemicals interact with the body. Pregnant women and the developing fetus may be particularly sensitive to the effects of wildfire PM_2.5. Previous studies have associated wildfire smoke with preterm birth. This study builds on previous work by including a large number of participants from across the country, accounting for other risk factors, and looking closely at how the timing, intensity, or duration of smoke exposures affects birth outcomes.

What were the study results?

Nearly all pregnant participants (99.2%) experienced at least one day of wildfire smoke, with an average of 22 smoke days during pregnancy. The study found that higher average wildfire smoke exposure during pregnancy was linked to a slight increase in risk for preterm birth. The connection was clearer in the Western U.S., especially with more intense or longer-lasting smoke events. Preterm birth was also associated with exposure to smoke days in mid-to-late pregnancy at the national level.

What was this study's impact?

The study highlighted that exposure to wildfire-specific PM_2.5, particularly at higher intensities and durations, is a risk factor for preterm birth. This is especially relevant in the Western U.S., where associations were more pronounced.

Who was involved?

The study included 20,034 pregnant participants who gave birth between 2006 and 2020, recruited from 30 ECHO Cohort Study Sites with residences during pregnancy in all 48 contiguous US states and the District of Columbia across the U.S.

What happened during the study?

The study tracked how much wildfire smoke pregnant participants were exposed to based on where they lived. Researchers looked at both the amount and duration of smoke, including stretches of smoky days in a row. They then used statistical methods to see if greater smoke exposure was linked to a higher risk of preterm birth, while also accounting for other health and social factors.

What happens next?

Future research could help identify regional differences in the effects of wildfire exposure, how wildfire smoke interacts with other risks like extreme heat, which parts of the smoke are most harmful, and how well different prevention strategies work to reduce exposure and related health outcomes.

Where can I learn more?

Access the full journal article, titled “Wildfire-specific fine particulate matter and preterm birth: a US ECHO Cohort analysis,” in Lancet Planetary Health.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published November 3, 2025

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Wildfire Smoke Exposure May Be Linked to Higher Risk of Preterm Birth, ECHO Study Finds

Children in High Gun Violence Areas Less Likely to Report Excellent Health, ECHO Study Finds

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Children in High Gun Violence Areas Less Likely to Report Excellent Health, ECHO Study Finds

Authors: Aruna Chandran, Emily Knapp, Nandita Somayaji, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Gun violence has been the leading cause of death in children and teens in the United States since 2021. In addition to fatalities, exposure to gun violence in communities has been linked to adverse mental health outcomes in children. However, most prior studies have focused on mental health effects in older children and have not fully examined developmental or physical health impacts in younger children. This study aimed to explore the association between neighborhood-level gun violence and the general health status of children nationwide.

What were the study results?

The study found that parents of children living in areas with high levels of gun violence were 20% less likely to report their child’s health as excellent or very good compared with children who had experienced less gun violence, even after accounting for age and neighborhood economic disadvantage. This association was consistent across age groups, with both younger and older children in high gun violence areas less likely to report excellent or very good health. The effect was strongest in children that lived in neighborhoods with high poverty and high gun violence, where they were 23% less likely to be reported as having excellent or very good health.

What was the study's impact?

The findings underscore the importance of community violence prevention efforts and the need to strengthen our understanding of community risk factors such as gun violence that hinder optimal child growth and development.

Who was involved?

The study included 13,450 children from birth to 17 years old from 56 ECHO Cohort Study Sites.

What happened during the study?

Researchers used data from the Gun Violence Archive to identify how much gun violence occurred in different neighborhoods, categorized into low, medium, and high levels. Then they looked at how parents rated their children’s overall health and compared it across neighborhoods. A statistical model was used to measure the link between children’s health and the amount of gun violence in their neighborhood.

What happens next?

Future research following children over time could help researchers better understand how exposure to gun violence affects children's health as they grow. Additional studies could also help researchers separate the impacts of gun violence exposure from other factors and explore how and why this exposure influences children’s health.

Where can I learn more?

Access the full journal article, titled “Associations between neighborhood-level gun violence and child general health status An ECHO Cohort analysis,” in Injury.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published November 2025

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Children in High Gun Violence Areas Less Likely to Report Excellent Health, ECHO Study Finds

The BREATHE Study: Bronchiolitis Recovery and Use of HEPA Filters

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Study Summary: Lay Summary for Participant Families

The BREATHE Study: Bronchiolitis Recovery and Use of HEPA Filters

Author(s): The BREATHE Study Team

Why was this study conducted?

Bronchiolitis is an infection that affects the airways of a child. Babies with bronchiolitis may need hospital treatment. These babies may still have breathing problems, such as coughing and wheezing, after they go home.

Many things can affect a person’s ability to breathe. One of those things is the level of very small particles in the air. These particles are called PM2.5, which are particulate matter that is less than 2.5 micrometers across. That size is smaller than the size of most pollen and mold. The level of these very small particles in the air in someone’s home can be lowered by special air filters called high efficiency particulate air (HEPA) filters.

The BREATHE study was done to find out if HEPA filters used in a baby’s house can help them breathe better than if no filter is used in their house. Specifically, the study looked at how many days infants, who previously had bronchiolitis, had specific breathing problems such as coughing, wheezing, or other breathing problems.

What was done?

Babies chosen for this study were less than 12 months old and had been hospitalized for bronchiolitis for the first time. Babies were selected from 17 hospitals, each in a different state. A total of 228 families were given either 2 HEPA units or 2 control units (identical units but with filters removed). One unit was to be used in the baby’s sleep space and the other unit in a common room of the home. Families did not know which types of units they were given. Air quality monitors measured the level of very small particles (PM2.5) in their homes. Families reported the number of days that their babies had breathing troubles. These reports were done weekly for 6 months. At the end of the study, families learned whether they had been using HEPA units or control units. All families were then given new HEPA filters. They also received individual reports about the PM2.5 levels in their home.

What was found?

The number of days babies had breathing problems were counted. The number of problem days for the babies living in homes with HEPA filters were compared to the number of problem days for the babies living in homes that had control units. Generally, babies in homes with working HEPA units had fewer breathing problems than babies in homes with the control units. Babies in homes with HEPA units had an average of 5 fewer days with breathing problems than did babies in homes with the control units. However, because the difference between the 2 groups is quite small, it is not clear if the breathing improvement was related to HEPA filter use or due to chance. This does not mean that the HEPA filters were not useful. It only means that it could not be proven with this study.

Compared to those with control units, babies who had HEPA filter units in their home had a 9% lower chance of unscheduled healthcare visits, such as hospitalizations, emergency room visits, and doctor’s office visits for breathing problems, but the difference between the 2 groups is small and may be due to chance. Babies who had HEPA filter units running most of the time during the study had a 25% lower chance of unscheduled doctor’s office visits for breathing problems.

On average, homes with working HEPA units had average common room PM2.5 equal to 11 micrograms per cubic meter (μg/m3). On average, levels were higher in the common room of homes with control units (15 μg/m3). The difference was even bigger in the infant’s sleep space. On average, homes with HEPA units had sleep space PM2.5 equal to 11 μg/m3. On average, homes with control units had sleep space PM2.5 equal to 21 μg/m3.

What do the results mean?

Filtering air with a HEPA unit may help infants who have been in the hospital for bronchiolitis. Infants in houses with HEPA units may have fewer days of breathing trouble than infants in houses without HEPA units. However, we would need to do a larger study to know for sure.

Who sponsored the study?

This research was supported by the Environmental influences on Child Health Outcomes (ECHO) program, the Office of the Director, National Institutes of Health.

Appreciation

The authors appreciate the children and families whose participation made the research possible.

The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Lay Summary for the BREATHE Study (for participant distribution)
cIRB # 274137 V-01 (27-October-2025)

ECHO Study Examines the Effects of COVID-19–Related Changes in Caregiver and Child Behavior on Youth Mental Health

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ECHO Study Examines the Effects of COVID-19–Related Changes in Caregiver and Child Behavior on Youth Mental Health

Authors: Amy Margolis, Andrew Law, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

The United States is facing a growing youth mental health crisis with a significant increase in mental or behavioral health conditions, partly linked to changes during the COVID-19 pandemic. This study examined changes in family hardships, behaviors, and coping strategies during the COVID-19 pandemic and evaluated whether these changes were associated with youth pandemic-related post-traumatic stress (PTS) symptoms.

What were the study results?

The study identified two groups of families based on their experiences of hardships, changes in daily behaviors, and coping strategies during COVID-19. The first group had minimal changes in their lifestyle and behaviors, while the second group had significant changes. The low change group included a higher proportion of Black families, single-parent households, and lower income and education levels.

Children and teens in the group with significant changes had higher Pandemic-related Traumatic Stress Scale (PTSS) scores compared to the group with minimal changes. Some aspects of parent or caregiver experiences, including their ability to isolate during the pandemic, were associated with lower PTSS scores in children. Youth whose parents or caregivers reported no change in their own behaviors were more likely to report lower PTSS scores. Changes in youth health behaviors (like eating, physical activity, and media use) and access to healthcare were important factors related to PTSS scores. Stability in these areas was linked to lower PTSS scores. The use of coping strategies by children and teens did not significantly reduce PTSS scores. Some coping strategies, like increased media use and substance use, were linked to higher PTSS scores.

What was the study's impact?

This study provides valuable insight that could help improve youth mental health now and in the wake of future public health emergencies. It demonstrates the importance of stability in health behaviors, access to healthcare, and the ability to isolate safely as key factors in reducing youth PTS symptoms.

Who was involved?

The participants included 9,139 youth and their parents or caregivers from across the United States, including 7,786 children (aged 2-12 years) and 1,353 teens and young adults (aged 13-21 years).

What happened during the study?

The study looked at information from ECHO families between April 2020 and August 2021 to understand how the pandemic affected them. Researchers grouped families into different categories based on their experiences and background characteristics from before the pandemic. The researchers then looked at symptoms of PTS in both children and teens within these family groups. The study explored how COVID-19 influenced family hardships, changes in parent and child behavior, and the ways families coped.

What happens next?

Future studies could help researchers examine what factors contribute to ongoing PTS symptoms or the occurrence of mental health diagnoses. Interviewing participants about acute stress when collecting PTSS survey responses could also help researchers confirm the validity of the survey.

Where can I learn more?

Access the full journal article, titled “Changes to Family Life, Youth COVID-19 Pandemic-Related Traumatic Stress, and the Youth Mental Health Crisis,” in the Journal of Clinical Child & Adolescent Psychology.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published October 17, 2025

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ECHO Study Examines the Effects of COVID-19–Related Changes in Caregiver and Child Behavior on Youth Mental Health

PFAS Exposure During Pregnancy Not Associated with Behavior Issues in Children, ECHO Study Finds

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PFAS Exposure During Pregnancy Not Associated with Behavior Issues in Children, ECHO Study Finds

Author(s): Catherine Bulka, Rebecca Fry, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of man-made chemicals used in some consumer and industrial products like cookware, stain-resistant fabrics, and foams used to fight fires. These substances are often referred to as “forever chemicals” because they don’t break down easily, causing them to build up in water, soil, and air. Previous findings on the effects of prenatal PFAS exposure on child behavior have been inconclusive due to small sample sizes, limited exposure variability, and differing measures of child behavior. This study looked at the relationship between PFAS exposure during pregnancy and child behavior using harmonized measurements collected from many mother-child pairs from across the United States.

What were the study results?

Most of the PFAS detected in pregnant mothers were not clearly linked to behavior problems in their children overall. Children whose mothers had medium levels of exposure to perfluorohexane sulfonate (PFHxS) during pregnancy showed more emotional problems, like being easily upset or withdrawn, especially when they were preschoolers. However, this pattern was not seen at very high or low levels of PFHxS exposure. There were no strong connections between PFAS exposure before birth and behavior problems when the children were older (school-age). Looking at combined exposures to multiple PFAS also did not show any clear relationship with child behavior.

What was the study's impact?

While most PFAS showed no association with behavioral problems, some suggestive, non-linear relationships emerged, indicating that these exposures may influence brain development in complex and unexpected ways. Overall, the study did not find strong or steady links between PFAS exposure during pregnancy and child behavior problems. More research may be needed, especially about newer PFAS replacement chemicals and exposures that happen after birth.

Who was involved?

The study included children from nine ECHO Cohort study sites across the U.S., including 1,723 preschool-age children (1.9-5.9 years) and 627 school-age children (6-15 years).

What happened during the study?

During the study, researchers measured PFAS levels in blood samples collected from mothers between 2- and 42-weeks’ gestation. Later, the researchers assessed children’s behavior using the Child Behavior Checklist (CBCL) when they were preschool- or school-aged. They then used statistical methods to evaluate potential associations between prenatal exposure to PFAS and PFAS mixtures and child behavioral problems.

What happens next?

Future studies could help researchers assess the effects of PFAS exposures during the postnatal period, which may be a more relevant window for childhood brain development and behavioral issues. Additionally, as some PFAS are being phased out of consumer products and replacements are emerging, future studies could help researchers understand the potential effects of exposures to these newer replacement chemicals.

Where can I learn more?

Access the full journal article, titled “Prenatal Exposure to Per- and Polyfluoroalkyl Substances: Association with Child Behavior in the Environmental influences on Child Health Outcomes (ECHO) Cohort,” in Environment International.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published September 5, 2025

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PFAS Exposure During Pregnancy Not Associated with Behavior Issues in Children, ECHO Study Finds

Toddler Emotional and Behavioral Problems Decreased Slightly During Pandemic, ECHO Study Finds

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Toddler Emotional and Behavioral Problems Decreased Slightly During Pandemic, ECHO Study Finds

Authors: Lauren Shuffrey, Anahid Akbaryan, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

The COVID-19 pandemic disrupted family patterns and children’s environments, both of which play a role in early brain development. Early childhood is a period of rapid brain growth and increased sensitivity to environmental influences, making the early social environment important for children's health and well-being. Previous research raised concerns about the development of infants born during the pandemic, but there is limited evidence on how the pandemic affected the behavioral and emotional well-being of toddlers. In this study, researchers wanted to look at the association between growing up during the pandemic and behavioral outcomes in toddler-aged children.

What were the study results?

The study found that children who experienced the pandemic had fewer emotional and behavioral problems compared to children born and assessed before the onset of the pandemic, based on results from the Preschool Child Behavior Checklist (CBCL). Specifically, their scores for internalizing problems, such as anxiety or sadness, were about 1.5 to 2 points lower, and their scores for externalizing problems, such as aggression or hyperactivity, were about 1.7 to 3.2 points lower than those born and assessed before the pandemic.

Although these differences were small, researchers report that they were consistent. The study also found that these links between growing up during the pandemic and lower emotional and behavioral problems were significantly stronger for children whose mothers did not have a bachelor’s degree.

What was the study's impact?

The study suggests that toddler-age children may have shown resilience despite the disruptions of the pandemic. These findings could help identify potential protective factors that could have buffered the impact of the pandemic on child behavior and inform future interventions to support children's well-being during and after global crises.

Who was involved?

The study included 3,438 toddlers (average age of 2 years) across the U.S. and Puerto Rico. Researchers grouped children based on when they were born and when they were assessed: before the pandemic, born before but assessed after March 2020, or both born and assessed during the pandemic.

What happened during the study?

During the study, researchers compared young children’s behavior and emotions before and during the pandemic using data from the ECHO Cohort collected between September 2009 and July 2023. Parents filled out the Preschool CBCL, a commonly used tool to assess the child’s emotions and behaviors, like anxiety, sadness, or hyperactivity. Researchers then analyzed these results to see how the pandemic may have affected children’s emotional and behavioral well-being.

What happens next?

Further research could help researchers identify potential protective factors that may have promoted resilience among children whose daily life was disrupted by the COVID-19 pandemic.

Where can I learn more?

Access the full journal article, titled “COVID-19 pandemic exposure and toddler behavioral health in the ECHO Program,” in JAMA Network Open.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published September 3, 2025

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Toddler Emotional and Behavioral Problems Decreased Slightly During Pandemic, ECHO Study Finds

PFAS Exposure Associated with Changes in Gut Microbiome During Pregnancy

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PFAS Exposure Associated with Changes in Gut Microbiome During Pregnancy

Authors: Michael Petriello, et al.

Who sponsored this study?

The Environmental influences on Child Health Outcomes (ECHO) Program, Office of the Director, National Institutes of Health supported this research.

Why was this study needed?

Per- and polyfluoroalkyl substances (PFAS) are a class of thousands of man-made chemicals that are used in various industrial processes and consumer products, including cookware, stain-resistant fabrics, and foams used to fight fires. PFAS can also build up in the environment, contaminating water, food, and air. Because PFAS can last a long time without breaking down, these chemicals can also build up in biological tissues, including the gut lining. PFAS exposure has previously been linked to diseases of the cardiovascular, immune, endocrine, reproductive, and metabolic systems.

Recent studies have shown that PFAS exposure may affect a person’s gut microbiome, the ecosystem of bacteria and other microbes that live in the gut. The composition of the gut microbiome is dependent on a variety of factors, including diet, lifestyle, and exposure to environmental chemicals. These microbes often help aid digestion, support immune health, or protect against pathogens. Changes in the maternal microbiome may impact multiple pregnancy health outcomes related to metabolism and inflammation. Therefore, it is important to identify environmental factors that may affect microbiome health during pregnancy.

What were the study results?

In both sites, prenatal PFAS exposure did not have a significant effect on the diversity of microbes in the maternal gut microbiome. However, the study found there was a significant association between prenatal PFAS exposure and the relative abundance of specific types of bacteria in the maternal gut microbiome. Associations between PFAS exposure and gut microbiome varied by study site, with certain types of bacteria being site-specific and not shared between the Michigan and Atlanta sites.

What was this study's impact?

The effect of PFAS exposure on maternal gut microbiome composition may have broader implications for the health of both the mother and baby. Decreasing exposure to pollutants such as PFAS can improve health outcomes, but complimentary interventions focused on improving microbiome health and resiliency may also help to combat the health effects of environmental chemicals.

Who was involved?

The study included 162 pregnant participants from ECHO study sites in Atlanta and Michigan. The Michigan site (Michigan Archive for Research on Child Health Cohort) included 61 predominantly non-Hispanic White (90.2%) participants. The Atlanta site (Atlanta African American Maternal Child Cohort) included 101 participants who self-identified as Black or African American (100%).

What happened during the study?

Researchers measured PFAS exposure during early or late pregnancy. Later in pregnancy, researchers collected microbiome samples from the mother’s stool to evaluate the types of bacteria present and the bacterial diversity. Statistical methods were used to understand the relationship between PFAS exposure and microbiome composition and diversity.

What happens next?

Future studies could help researchers understand how these microbiome changes are related to maternal and child health outcomes.

Where can I learn more?

Access the full journal article, titled “Prenatal PFAS exposure and outcomes related to microbiome composition and diversity in later pregnancy,” in Environmental Research.

The content is the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Published August 15, 2025

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PFAS Exposure Associated with Changes in Gut Microbiome During Pregnancy