Exposure to Flame-retardant Chemicals During Pregnancy Associated with Differences in Child Growth Patterns

Authors: Anne P. Starling, Jessie P. Buckley, Deborah Bennett, 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?

Organophosphate esters (OPEs) are chemicals widely used as flame retardants and plastic softeners in a variety of household and industrial products. Pregnant women are commonly exposed to these chemicals. While prior studies have examined the effects of OPE exposure during pregnancy on birth outcomes, less is known about how prenatal exposure to these chemicals affects children’s growth patterns beyond infancy. Understanding how early-life environmental exposures are associated with child growth trajectories is important because childhood growth rates can be linked to later risk of obesity and heart disease. This study specifically examined the relationship between OPE exposure during pregnancy and child height, weight, and body mass index (BMI).

What were the study results?

The study found that exposure to specific OPEs during pregnancy was associated with differences in child growth rates between ages 2 and 10 years. Higher prenatal exposure to bis (1,3-dichloro-2-propyl) phosphate (BDCPP) was associated with faster increases in weight and height during early childhood (ages 2–5). In mid-childhood (ages 6–10), higher prenatal exposure to diphenyl phosphate (DPHP) was associated with faster increases in body mass index and weight. In contrast, prenatal exposure to bis(1-chloro-2-propyl) phosphate (BCPP) was associated with slower growth across multiple periods. Some associations differed by child sex and by maternal pre-pregnancy body mass index.

What was this study's impact?

These findings suggest that exposure to certain flame-retardant chemicals during pregnancy may be associated with children’s growth patterns. Because growth trajectories are linked to future obesity and metabolic health, these results underscore the importance of understanding and potentially reducing exposure to these widely used chemicals during pregnancy.

Who was involved?

The study included 4,566 mother-child pairs from 14 ECHO Cohort Study Sites across the United States. Researchers collected exposure data during pregnancy and collected growth data from ages 2 to 10 years.

What happened during the study?

Researchers measured nine chemical markers of OPE exposure in urine samples collected from pregnant participants. They later collected child weight and height measurements between ages 2 and 10 years, which were used to calculate each child’s BMI. The researchers then used statistical models to examine how prenatal OPE exposure was associated with rates of change in weight, height, and BMI.

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?

Future studies could help researchers better understand the biological mechanisms linking prenatal OPE exposure to child growth and examine whether reducing exposure during pregnancy could improve long-term child health outcomes. Additional studies may also explore the combined effects of multiple environmental chemical exposures during pregnancy and early childhood on the patterns of child growth patterns.

Where can I learn more?

Access the full journal article, titled “Gestational exposure to organophosphate ester flame retardants and child growth in weight, height, and body mass index at age 2-10 years: the Environmental influences on Child Health Outcomes Program” 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.

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Exposure to Flame-retardant Chemicals During Pregnancy Associated with Differences in Child Growth Patterns

Smoking During Pregnancy Linked to Mental Health Challenges in Children, ECHO Study Finds

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Smoking During Pregnancy Linked to Mental Health Challenges in Children, ECHO Study Finds

Authors: Kristine Marceau, 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?

Previous research has shown that children whose mothers smoked during pregnancy are more likely to develop behavior problems, particularly difficulties with acting out or following rules. However, it has been less clear whether prenatal smoking also increases the risk of mental health problems generally, or if it’s a specific risk for difficulties with acting out or following rules alone. Researchers from this study wanted to understand whether prenatal smoking contributes to co-occurring emotional and behavioral symptoms or specifically behavioral symptoms, and whether its effects differ by age or sex. This study helps address these gaps by examining which developmental periods may be especially sensitive to prenatal smoking effects and whether boys or girls are more vulnerable.

What were the study results?

Children exposed to smoking before birth were more likely experience multiple co‑occurring emotional and behavioral symptoms, and also to show more externalizing problems—such as attention problems, aggressive behavior, and rule‑breaking. These associations were observed across nearly all age groups and remained even after accounting for family history, background, and other exposures.

The strongest effects on mental health symptoms were seen in early childhood (under age 7) and early puberty (ages 9 to 12). There were very few differences between boys and girls. Only at ages 13-14 did boys seem to have more co‑occurring emotional and behavioral symptoms and externalizing-specific problems than girls. In general, both boys and girls were affected in similar ways.

What was the study's impact?

These results suggest that prenatal exposure to nicotine may increase the risk of mental health and behavioral problems. Because this study included a large number of children from different backgrounds, it helps clarify past research and contributes new insight about when certain problems tend to appear and how different symptoms may occur together.

Who was involved?

The study included 16,335 children and adolescents ages 1 to 18 from 55 U.S. ECHO Cohort Study Sites. All participants completed Child Behavior Checklist (CBCL) and Strengths and Difficulties Questionnaire (SDQ) behavioral assessments.

What happened during the study?

Researchers gathered standardized information about children’s behavior and created a simple score to show how many symptoms a child had and whether those symptoms were more emotional (such as sadness, anxiety) or behavioral (such as acting out, rule breaking). They then looked at these patterns across different age groups, while taking into account important factors such as the mother’s age and education, family mental health history, and exposure to smoke or other substances during and after pregnancy.

What happens next?

Future work could help researchers understand how timing, dose, and frequency of smoking during pregnancy correlates with child mental health. Future research could also use methods to separate the effects of family background from the effects of smoking itself and look more closely at how nicotine and other chemicals in smoke might affect children’s development.

Where can I learn more?

Access the full journal article, titled “Prenatal Smoking and Child Psychopathology Associations by Age and Sex in the ECHO Cohort,” in Development and Psychopathology.

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

Published April 6, 2026

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Smoking During Pregnancy Linked to Mental Health Challenges in Children, ECHO Study Finds

Stress During Pregnancy & Adverse Experiences in Mom’s Own Childhood May Be Associated with Child Mental Health, ECHO Study Finds

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Stress During Pregnancy & Adverse Experiences in Mom’s Own Childhood May Be Associated with Child Mental Health, ECHO Study Finds

Authors: Shaikh Ahmad, Alexandra Sullivan, Marie Churchill, Rosa Crum, Nicole Bush, 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 global rise in pediatric mental health problems has highlighted the importance of identifying factors that may affect children’s mental health. Previous research has suggested that maternal stress—both adverse experiences during the mother’s own childhood and stress during pregnancy—may affect child mental health, but large-scale, diverse studies examining both exposures together, and their effects across childhood and adolescence, are needed to help researchers identify effective screening and intervention strategies.

What were the study results?

The study found that mothers’ own adverse childhood experiences (ACEs)—such as abuse or neglect—and experiences of stress during pregnancy were each independently associated with a higher risk of mental health problems in their children, suggesting that maternal stressors during each period may have contributed to the child’s risk in a potentially accumulative manner. These effects on children included both internalizing (e.g., anxiety, depression) and externalizing (e.g., ADHD, behavior problems) mental health issues. The effects of maternal ACEs and pregnancy stress on child mental health problems were similar for boys and girls and were seen throughout childhood and adolescence.

What was the study's impact?

The findings from this diverse nationwide study strengthen the evidence showing that maternal stress before and during pregnancy can increase the risk for child mental health problems. These results also highlight the potential benefits across generations of early screening and intervention related to maternal stress and childhood adversity—not only in improving maternal health, but also in reducing mental health problems in children and teens.

Who was involved?

The study included 6,513 mother-child pairs enrolled in 34 ECHO Cohort Study Sites across 19 U.S. states, Washington, D.C., and Puerto Rico. Children ranged in age from 1.5 to 18 years old. The sample was racially, socioeconomically, and geographically diverse.

What happened during the study?

The researchers collected information from mothers on their childhood adverse experiences and stress during pregnancy. Later, a parent or caregiver provided information on the child’s mental health using either the preschool-age or school-age child behavior checklist (CBCL). Researchers then used statistical analyses to evaluate the relationship between maternal ACEs, pregnancy stress, and child mental health.

What happens next?

Additional research could help researchers identify other factors that may influence the risk of child mental health problems (e.g., paternal ACEs) and factors that could buffer this risk. The authors of this paper also suggest that increased screening for ACE exposure and current social needs in pregnant populations and enhanced access to prenatal mental health support could help to improve mental health for both mothers and their children.

Where can I learn more?

Access the full journal article, titled “Maternal Adverse Childhood Experiences and Prenatal Stress: Intergenerational Transmission and Offspring Mental Health in the ECHO Cohort,” in Psychological Medicine.

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

Published March 11, 2026

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Stress During Pregnancy & Adverse Experiences in Mom’s Own Childhood May Be Associated with Child Mental Health, ECHO Study Finds

Perceived Stress During Pregnancy Associated with Autism-related Traits in Children, ECHO Study Finds

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Perceived Stress During Pregnancy Associated with Autism-related Traits in Children, ECHO Study Finds

Authors: Luke Grosvenor, 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?

Many mothers experience higher levels of stress and other mental health challenges during pregnancy. Previous studies have found that pregnancy stress may be associated with increased risk of autism spectrum disorder (ASD) in children, but these studies have mostly focused on the occurrence of isolated adverse or stressful events that occur in the mother’s life during pregnancy. Fewer studies have measured general perceived stress among mothers during pregnancy. This study examined the potential association between perceived stress during pregnancy and autism-related traits in children and evaluated how that association may differ according to the child’s sex or the mother’s experience of depression during pregnancy.

What were the study results?

Higher perceived stress during pregnancy was associated with slightly more severe autism‑related traits in children. At higher prenatal perceived stress levels, children showed slightly higher scores on tests measuring social and behavioral traits related to autism. Children whose mothers had either moderate or high categorical stress scored higher than those whose mothers reported low or no stress. The link between pregnancy stress and autism‑related traits did not differ between boys and girls. The relationship between prenatal stress and autism‑related traits remained consistent even when the researchers accounted for mothers’ co-occurring prenatal depressive symptoms.

What was the study's impact?

Stress during pregnancy is normal and common to experience. While the results of this study indicate that there may be a small association between pregnancy stress and autism-related traits, they do not imply that stress during pregnancy causes autism spectrum disorder or autism-related traits to occur in children.

Who was involved?

The study included 4,115 mother–child pairs from 20 ECHO Cohort Study Sites across the United States. Children ranged in age from about 2.5 to 18 years old.

What happened during the study?

Mothers reported their stress levels during pregnancy using a standard questionnaire. Later, parents reported on their children’s autism-related traits using a validated survey. Researchers analyzed the data using statistical models that accounted for factors such as child age, sex, and study site.

What happens next?

Future studies could help researchers better understand the specific periods in pregnancy when stress may have the greatest association with child health and development and how other related social and emotional factors may influence this effect.

Where can I learn more?

Access the full journal article, titled “Associations between Prenatal Perceived Stress and Child Autism-Related Traits in the ECHO Cohort,” in The Journal of Pediatrics.

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

Published March 2, 2026

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Perceived Stress During Pregnancy Associated with Autism-related Traits in Children, ECHO Study Finds

Maternal Smoking During Pregnancy May Be Associated with Increased Childhood Blood Pressure, ECHO Study Finds

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Maternal Smoking During Pregnancy May Be Associated with Increased Childhood Blood Pressure, ECHO Study Finds

Authors: Lyndsey E. Shorey-Kendrick, Christine Ladd-Acosta, 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?

Blood pressure that is higher than normal in childhood, including diagnosed high blood pressure, can increase the risk of developing high blood pressure as an adult, which is a major risk factor for heart disease. Past studies looking at smoking during pregnancy and children’s blood pressure have had mixed results. Many relied on parents’ self-reports of smoking or focused only on systolic blood pressure, the top number in a blood pressure reading that reflects pressure when the heart beats. Fewer studies examined diastolic blood pressure, the bottom number that reflects pressure when the heart rests between beats.

To better understand these links, researchers needed a large U.S. study that included objective lab measures of smoking during pregnancy. Using data from the ECHO Cohort, researchers examined how smoking during pregnancy was related to both systolic and diastolic blood pressure in children.

What were the study results?

Children whose mothers smoked during pregnancy—whether occasionally or regularly—were more likely to have higher blood pressure and a greater risk of hypertension (higher than normal blood pressure at three or more doctors’ visits). The study distinguished between “any reported smoking,” which is based on what mothers shared in surveys or medical records, and “active smoking,” which is confirmed by a urine test for cotinine, a marker of recent tobacco use. Active smoking, identified by these lab tests, was linked to even higher blood pressure in children.

What was the study's impact?

This study reinforces that smoking during pregnancy is a risk factor for increased childhood blood pressure and hypertension and underscores the importance of smoking reduction during pregnancy for children’s heart health. The use of objective laboratory measures strengthens these findings and more accurately identifies children at risk.

Who was involved?

The study included 13,120 children born between 1999 and 2020 from 52 ECHO Cohort Study Sites in the U.S. All children had at least one blood pressure measurement taken between the ages of 3 and 18 years. A nearly equal number of male and female children from a range of sociodemographic groups were included.

What happened during the study?

Researchers collected smoking data from pregnant women using self-report surveys, medical records, and/or urine specimens. Children’s blood pressure was measured when they were between 3 and 18 years of age. Using these measurements, the researchers performed a statistical analysis to compare blood pressure levels between children exposed to smoking during pregnancy and children not exposed. The researchers also assessed whether there were any differences in the relationships between smoking and blood pressure by child sex.

What happens next?

More studies could help researchers better understand how smoking during pregnancy may contribute to higher blood pressure in children. Future studies could use biological measures of prenatal smoke exposure, which may help capture individual differences in how children are affected and make it easier to identify those at higher risk

Where can I learn more?

Access the full journal article, titled “Association of Maternal Smoking During Pregnancy with Childhood Blood Pressure and Hypertension in the ECHO Cohort,” in Circulation.

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

Published February 16, 2026

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Maternal Smoking During Pregnancy May Be Associated with Increased Childhood Blood Pressure, ECHO Study Finds

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Exposure to PM_2.5 Air Pollution During Pregnancy Associated with Lower Birthweight, ECHO Study Finds

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Exposure to PM_2.5Air Pollution During Pregnancy Associated with Lower Birthweight, ECHO Study Finds

Authors: Daniel Enquobahrie, Adaeze Wosu Nzegwu, 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?

Exposure to fine particulate matter (PM_2.5)—very small inhalable particles found in air pollution—is widespread and linked to various health risks. Previous research has examined the effects of PM_2.5exposure during pregnancy on birth outcomes, but gaps remain. More research is needed to understand whether there are critical windows during pregnancy when PM_2.5exposure is most impactful. This study aimed to address these gaps by investigating how the timing of PM_2.5exposure affects birth outcomes, such as birthweight and length of pregnancy, using data from the ECHO Cohort’s large, multi-site study structure. It also explored whether associations differ by infant sex and maternal race and ethnicity.

What were the study results?

Exposure to higher levels of PM_2.5during the first weeks of pregnancy was linked to babies being slightly smaller at birth and having a higher chance of being born small for their gestational age (smaller than average for the length of the pregnancy). There was no significant association between PM_2.5exposure and shorter pregnancies or preterm birth. For baby girls, higher PM_2.5exposure in early pregnancy seemed to affect their birth size more than for baby boys, suggesting that the baby's sex can make a difference in how air pollution affects growth. The effects of PM_2.5on birth outcomes like being born prematurely, birth size, or being small for gestational age varied depending on the mother's race and ethnicity.

What was this study's impact?

This study on PM_2.5 exposure during early pregnancy and birth outcomes can inform ongoing discussions on strategies for reducing PM_2.5 air pollution.

Who was involved?

The study included 19,108 mother-infant pairs from 51 ECHO Cohort Study Sites across the United States.

What happened during the study?

Researchers estimated PM_2.5 exposure for each pregnant participant based on residential address, accounting for moves during pregnancy. The researchers then assessed exposure for the whole pregnancy, each trimester, and specific windows in the first trimester. The researchers collected information on birth outcomes, including length of pregnancy and birthweight.

What happens next?

Further research could help investigators better understand the mechanisms underlying differences in air pollution vulnerability by infant sex, and by maternal race and ethnicity. Additional studies could also help researchers understand how other factors, such as diet and lifestyle, influence the relationship between PM_2.5exposure and birth outcomes.

Where can I learn more?

Access the full journal article, titled “Gestational fine particulate matter exposure and perinatal outcomes in the ECHO cohort: Associations across pregnancy windows,” 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 March 1, 2026

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Exposure to PM_2.5Air Pollution During Pregnancy Associated with Lower Birthweight, ECHO Study Finds

Exposure to Certain Flame-retardant Chemicals During Pregnancy May Be Linked with Decreased Cognitive Function in Young Children, ECHO Study Finds

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Exposure to Certain Flame-retardant Chemicals During Pregnancy May Be Linked with Decreased Cognitive Function in Young Children, ECHO Study Finds

Authors: Akhgar Ghassabian, 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?

Organophosphate esters (OPEs) are chemicals widely used as flame retardants and plastic softeners in a variety of household and industrial products, and previous studies suggest they can affect child brain development. With increasing human exposure to these chemicals, especially during sensitive periods like pregnancy, there has been concern about the potential impact on child cognitive development. Previous studies have found mixed results, highlighting the need for a large, contemporary cohort study to clarify these associations and examine possible sex differences.

What were the study results?

When pregnant women had higher urine levels of diphenyl phosphate (DPHP), a compound produced during the breakdown of certain OPEs in the human body, their children tended to have slightly lower scores on tests of mental skills at ages 4–6. This pattern was seen in boys and girls. Boys whose mothers had higher levels of certain other chemicals linked to OPE exposure during pregnancy scored higher on these tests, but this was not true for girls. This finding was unexpected, so more research may be needed to understand the biological mechanism underlying this association.

What was this study's impact?

Results from this large contemporary cohort of mother–child pairs in the U.S. suggest that OPE exposure during pregnancy may be associated with minor decreases in cognitive functioning in children. Considering that DPHP is a widely detected marker of OPE exposure in the U.S. population, the overall impact of this effect may be significant.

Who was involved?

The study included 831 mother–child pairs from three ECHO Cohort Study Sites in the United States. The study population was predominantly non-Hispanic White and highly educated, which may limit generalizability.

What happened during the study?

Pregnant participants provided urine samples for measurement of nine OPE chemicals. Researchers assessed child mental skills using standardized intelligence scales when children were between 4 and 6 years old. Researchers then used statistical analyses to examine associations between OPE exposure and childhood cognition.

What happens next?

Additional studies could help researchers better understand the biological pathways underlying these associations. Additional studies could also help clarify the association between some chemical markers of OPE exposure and higher cognitive scores among boys.

Where can I learn more?

Access the full journal article, titled “Prenatal exposure to organophosphate ester flame retardants and child cognition: findings from the environmental influences on child health outcomes cohort,” in Environmental Pollution.

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

Published February 1, 2026

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Exposure to Certain Flame-retardant Chemicals During Pregnancy May Be Linked with Decreased Cognitive Function in Young Children, ECHO Study Finds

ECHO Study Investigates Relationship Between Chemical Exposures, Pregnancy Stress, & Birth Outcomes

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ECHO Study Investigates Relationship Between Chemical Exposures, Pregnancy Stress, & Birth Outcomes

Authors: Stephanie Eick, Anne Dunlop, 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?

Most previous research on the effects of chemical exposures on birth outcomes has focused on a small number of well-established chemicals, such as bisphenol A (BPA) and certain phthalates. However, there are over 350,000 chemicals registered for global use, and the impact of many emerging or understudied chemicals on birth outcomes is not well understood. Additionally, prior studies have not adequately considered how different kinds of maternal stress (such as anxiety, depression, and adverse childhood experiences) might influence the effects of chemical exposures during pregnancy. This study examined a broader range of chemicals and evaluated the role of stress in influencing their associations with birth outcomes.

What were the study results?

Exposure to chemicals found in certain consumer and industrial products (such as phthalates, bisphenols, and insecticides) was associated with shorter pregnancies among women who experienced anxiety during pregnancy or in the early postpartum period. Depression modified how exposure to certain chemicals (such as phthalates, parabens, and insecticides) affected birthweight and length of pregnancy. Some chemicals positively correlated with length of pregnancy (duration) for mothers with more depression, while others were associated with lower birthweights when mothers had more depression symptoms. The study suggested that the effects of a mother’s stress on the relationship between chemical exposures and birth outcomes depended on the type of chemical and type of stressor experienced.

What was this study's impact?

This study found that exposure to chemicals commonly found in consumer products was associated with shorter pregnancies and lower among women experiencing anxiety during or after pregnancy. While the results were mixed, the researchers observed some patterns where effects of chemical exposures were strongest among mothers who experienced depression and anxiety. These findings suggest that screening for depression and anxiety during pregnancy could help identify women who may be at a higher risk of adverse birth outcomes.

Who was involved?

The study included 1,556 mother-child pairs from 11 ECHO Cohort Study Sites. 810 of these participants provided information on perceived stress, depression, and anxiety. Additionally, participants provided information on adverse childhood experiences.

What happened during the study?

Pregnant participants provided urine samples, which researchers analyzed for 113 chemicals from 10 chemical classes. Pregnant participants also reported on their stress, depression, anxiety, and adverse childhood experiences. Researchers collected information on each mother’s birth outcomes, including the length of their pregnancy (in weeks) and the baby’s birthweight. The researchers performed statistical analyses to examine associations between chemical exposures, stress, and birth outcomes.

What happens next?

Additional studies looking at the combined effects of multiple combined exposures could help researchers better understand the role of these factors in influencing birth outcomes. Future research could also further investigate potential biological effects of maternal adverse childhood experiences.

Where can I learn more?

Access the full journal article, titled “Psychosocial Stressors as Modifiers of the Associations Between Well-Studied and Understudied Chemicals and Birth Outcomes in the ECHO Cohort,” in Environmental Pollution.

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

Published January 15, 2026

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ECHO Study Investigates Relationship Between Chemical Exposures, Pregnancy Stress, & Birth Outcomes

Sleep Habits Vary for Children Living in Medically Underserved Areas But Not in Rural Communities, ECHO Study Finds

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Sleep Habits Vary for Children Living in Medically Underserved Areas But Not in Rural Communities, ECHO Study Finds

Authors: Brittany Lancaster, Christy W. Hockett, Anna Wallisch, 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?

People who live in rural communities or in medically underserved areas often face challenges like long travel distances, limited medical services, and fewer health resources. A medically underserved area is defined as having too few primary care providers, high infant mortality, or high poverty and/or high elderly population. These barriers make it harder to get routine care and treatment, which can worsen existing health disparities between communities. Few studies have evaluated how living in a rural or medically underserved area shapes children’s access to health-promoting resources. Because these geographic and healthcare barriers can influence key behaviors such as sleep, this study aimed to clarify how these conditions could contribute to differences in youth sleep health across the United States. Learning about these differences could help identify which groups may need more support and guide efforts to reduce health disparities.

What were the study results?

Children living in medically underserved areas tended to have different sleep patterns than those in communities with more resources. They generally went to bed later, woke up later, and were less likely to get the recommended amount of sleep for their age, especially among children ages 1 – 12 years. By contrast, differences between rural and non‑rural children were small; rural children typically went to bed and woke up earlier, while preschoolers in non‑rural areas slept longer overall because they napped more often. Bedtime habits were also mostly similar across all groups, though toddlers and teens in well-resourced areas were more likely to follow a regular bedtime routine, and preschoolers in underserved areas were more likely to use electronics before bed.

What was the study's impact?

This study suggests that living in a medically underserved areas may contribute to differences in children’s sleep health, with youth in medically underserved areas reporting later bedtimes, later wake times, and lower rates of getting the recommended amount of sleep. In contrast, only small differences were observed between children from rural and nonrural communities, suggesting that rurality alone may play a smaller role in shaping sleep patterns. The slight differences in bedtime habits—such as routines and screen use—indicate that family practices may vary across communities but are not the primary drivers of these sleep disparities. Together, these findings highlight the need for targeted efforts to support healthy sleep in medically underserved communities and suggest that researchers should continue to examine rurality and medically underserved status separately to better understand how different environments influence children’s sleep.

Who was involved?

The study included 22,234 youth aged 1–17 years. Of these, 6,976 lived in a medically underserved area and 908 of them lived in areas that were both medically underserved and rural. Overall, 1,853 youth lived in rural communities, and roughly half (945) of these lived in rural areas that were not medically underserved.

What happened during the study?

Researchers used participants' residential addresses and federal guidelines to sort children into four groups based on whether they lived in rural areas, medically underserved areas, both, or neither. Using parent or self-completed questionnaires, they collected information about children’s sleep, such as how long they slept, what time they went to bed and woke up, and how long it took them to fall asleep. They also asked about bedtime habits such as routines and screen use. The researchers then compared these sleep patterns across the different groups and looked at whether the results varied by age, from toddlers through adolescents.

What happens next?

Future studies could help communities develop effective sleep health programs, especially in medically underserved areas, potentially through daycares, community centers, and schools.

Where can I learn more?

Access the full journal article, titled “Exploring Sleep Outcomes in Youth Across Settings: Are There Differences based on Rurality or Medically Underserved Status in the ECHO Cohort?” in Sleep Medicine.

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

Published December 27, 2025

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Sleep Habits Vary for Children Living in Medically Underserved Areas But Not in Rural Communities, ECHO Study Finds

Higher Early-Life PM_2.5 Linked to Higher Childhood Blood Pressure, While Prenatal NO₂ Exposure Associated with Lower Blood Pressure, ECHO Study Finds

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Higher Early-Life PM_2.5 Linked to Higher Childhood Blood Pressure, While Prenatal NO₂ Exposure Associated with Lower Blood Pressure, ECHO Study Finds

Authors: Yu Ni, Catherine Karr, 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 prevalence of high blood pressure (HBP) in children is rising globally, with long-term health consequences such as heart disease and impaired kidney function. Childhood high blood pressure has increased by nearly 80% over the past two decades, especially in countries with higher obesity rates like the United States. Since high blood pressure in childhood can both track into adulthood and affect children’s health directly, ECHO researchers wanted to understand the influence that environmental factors such as pollution can have on childhood blood pressure. Specific pollutants such as fine particulate matter (PM_2.5) and nitrogen dioxide (NO₂) are emitted from vehicles, power plants, and industrial processes. These pollutants are known contributors to heart disease in adults, but their impact on children’s blood pressure is less clear. Previous research has been inconclusive, often limited to single-site studies. Researchers used the ECHO Cohort’s large, multi-site study structure to help clarify these associations.

What were the study results?

Children who were exposed to more PM_2.5 air pollution before and after birth had slightly higher blood pressure on average between ages 5 and 12. Specifically, higher PM_2.5 exposure during the first trimester was linked to a more pronounced increase in systolic blood pressure and a greater risk of high blood pressure in childhood, indicating that early pregnancy may be a particularly sensitive period. When their mothers were exposed to more NO₂ air pollution during pregnancy, children unexpectedly had lower blood pressure. The study found that NO₂ exposure during mid- to late pregnancy was associated with slightly lower blood pressure levels, particularly in the second trimester, and was not linked to a higher risk of high blood pressure. These findings overall suggest that timing of pollution exposure during pregnancy matters for children’s blood pressure later in life.

What was this study's impact?

The study provides additional evidence that exposure to PM_2.5 may be associated with adverse effects on childhood cardiometabolic health, even at low exposure levels. The observed association between prenatal NO₂ exposure and decreased childhood blood pressure is unexpected and suggests that further research may be needed to better understand the underlying mechanisms as well as other environmental factors that may influence this relationship.

Who was involved?

The study included 4,863 U.S. children aged 5–12 years and their mothers, drawn from 20 ECHO Cohort Study Sites.

What happened during the study?

Researchers estimated how much outdoor air pollution children were exposed to at their homes, focusing on PM_2.5and NO₂. They examined exposure during each trimester of pregnancy, across the full pregnancy, and during the child’s first two years of life. Children’s blood pressure was measured between ages 5 and 12 and compared with typical levels for children of the same age, sex, and height; blood pressure was considered high if it fell within the top 10 percent of the distribution.

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

What happens next?

More research could help investigators better understand why exposure to nitrogen dioxide during pregnancy was linked to lower, rather than higher, blood pressure in children. This could include exploring possible biological explanations and looking at whether other environmental exposures that occur alongside air pollution may be influencing this finding, such as transportation noise exposure.

Where can I learn more?

Access the full journal article, titled “Pre- and Postnatal Exposure to PM_2.5 and NO₂ and Blood Pressure in Children: Results from 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 23, 2025

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Higher Early-Life PM_2.5 Linked to Higher Childhood Blood Pressure, While Prenatal NO₂ Exposure Associated with Lower Blood Pressure, ECHO Study Finds