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

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.

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?

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

ECHO Study Finds Exposure to Air Pollution During Early Pregnancy Associated with Lower Birthweight

Posted on February 6, 2026March 11, 2026 by Jodi Snare

Exposure to fine particulate matter (PM_2.5)—very small inhalable particles found in air pollution—during early pregnancy was associated with babies being slightly smaller at birth, according to a new ECHO Cohort study led by Daniel Enquobahrie, PhD, MD, MPH of the University of Washington School of Public Health and Adaeze Wosu Nzegwu, PhD, MPH of Johns Hopkins Bloomberg School of Public Health.

Exposure to PM_2.5 is widespread and linked to various health risks, including respiratory, cardiovascular, and metabolic diseases. 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. For this study, researchers used information from 19,108 mothers and their babies from 51 ECHO Cohort Study Sites across the United States to evaluate how timing of PM_2.5 exposure affects birth outcomes. They also explored whether associations differ by infant sex and maternal race and ethnicity.

Key Takeaways include:

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 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.

“This study on PM_2.5 exposure during pregnancy and birth outcomes can inform ongoing discussions on regulations that impact PM_2.5 exposure, such as traffic-related air pollution.” said Dr. Enquobahrie.

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.

This collaborative research, titled “Gestational fine particulate matter exposure and perinatal outcomes in the ECHO cohort: Associations across pregnancy windows,” is published in Environmental Research.

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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.

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 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

Pregnancy Stress Can Influence Relationship Between Chemical Exposures & Birth Outcomes, ECHO Study Finds

Posted on January 7, 2026January 7, 2026 by Jodi Snare

Stress, anxiety, and depression during pregnancy and maternal adverse childhood experiences may influence the relationship between certain chemical exposures and birth outcomes, according to a new ECHO Cohort study led by Stephanie Eick, PhD, MPH and Anne Dunlop, MD, MPH of Emory University.

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 included 1,556 mother-child pairs from eleven ECHO Cohort Study Sites across the United States. Researchers analyzed urine samples from pregnant participants for 113 different chemicals from 10 chemical classes. Participants also reported on their stress, depression, anxiety, and adverse childhood experiences, allowing researchers to evaluate how these factors affect the relationship between different chemical exposures and birth outcomes.

Key Takeaways include:

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 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.

“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,” said Dr. Eick.

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.

This collaborative research, titled “Psychosocial Stressors as Modifiers of the Associations Between Well-Studied and Understudied Chemicals and Birth Outcomes in the ECHO Cohort,” is published in Environmental Pollution.

Read the research summary.

Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water

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Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water

Authors: Anne Nigra, 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?

Regulated U.S. public drinking water is a source of exposure to arsenic. Because arsenic occurs naturally, water that comes in contact with certain rocks and soils may contain it. Contamination from various industrial processes also contributes to increased levels of arsenic in some areas. Prenatal exposure to arsenic has been associated with adverse birth outcomes, including preterm birth and low birthweight. Researchers studied how arsenic in public drinking water—at levels below the federal limit—may affect birth outcomes in the ECHO Cohort. Previous evidence has been limited to private well exposures, studies using urinary biomarkers, and single-site studies with limited racial, ethnic, and geographic diversity.

What were the study results?

The study found that when pregnant women lived in areas with publicly reported high levels of arsenic in public drinking water, even at levels below the current federal safety standard of 10 micrograms per liter, their babies were more likely to be born with low birthweight (weighing less than 5 lbs 8 oz) or are small for their gestational age (smaller than babies born at the same number of weeks of pregnancy). These patterns were seen across several racial and ethnic groups, including White, Black, and Hispanic/Latino families. For example, babies born to Hispanic/Latino parents were about 40% more likely to have low birthweight with just a 5 microgram-per-liter increase in water arsenic. The study also found that babies born to Black parents had higher risks of being born early, with low birthweight, or smaller for their gestational age. Similar risks were observed among babies born to American Indian, Alaskan Native, Native Hawaiian, and Pacific Islander parents.

What was this study's impact?

The study shows that even low levels of arsenic in public drinking water may increase the risk of babies being born too early, too small, or underweight.

Who was involved?

Participants included 13,998 birthing mother-infant pairs from the ECHO Cohort.

What happened during the study?

Researchers estimated how much arsenic people were exposed to through public drinking water during pregnancy by combining water quality data with where each person lived each month. They then looked at whether that exposure was linked to outcomes like being born early (preterm birth), having a low birthweight, or being small for their gestational age.

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 research could help researchers understand how current efforts to reduce arsenic in drinking water are working—whether those efforts happen across the country, in local communities, in homes, or for individuals. Studies could also help identify where arsenic levels are highest, which may support ongoing work to make sure communities have safe drinking water.

Where can I learn more?

Access the full journal article, titled “Public water arsenic and birth outcomes in the Environmental influences on Child Health Outcomes 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 June 16, 2025

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Adverse Birth Outcomes May be Associated with Arsenic Levels in Public Drinking Water

Exposure to Low Levels of Arsenic in Public Drinking Water Linked to Lower Birthweight, Preterm Birth, Study Finds

Posted on June 16, 2025August 27, 2025 by Jodi Snare

Babies born to mothers potentially exposed to low levels of arsenic in public drinking water—even at levels below the federal safety standard—were more likely to be born preterm, with lower birthweight, or be smaller than expected, according to a study funded by the National Institutes of Health’s Environmental influences on Child Health Outcomes (ECHO) Program.

While the U.S. Environmental Protection Agency sets a maximum contaminant level of 10 micrograms per liter for arsenic in public water systems, this study examines how even lower-level arsenic exposures may still affect pregnancy outcomes in a large population. Previous research largely focused on private wells or smaller study groups.

Because arsenic occurs naturally, water that comes in contact with certain rocks and soils may contain it. Contamination from various industrial processes also contributes to increased levels of arsenic in some areas.

“Most U.S. residents rely on public drinking water, and our findings suggest that further reducing arsenic in public water systems could be an important step to improve infant health across the U.S.,” said Anne Nigra, PhD, of Columbia University’s Mailman School of Public Health. “Even low levels of arsenic in public drinking water were associated with low birthweight and other adverse birth outcomes in U.S. infants.”

Key takeaways include:

Potential arsenic exposure during pregnancy—even at levels below the current federal safety standard—may be linked to adverse birth outcomes.
Mothers exposed to higher levels of arsenic in public drinking water were more likely to have babies born with low birthweight or smaller than expected for the number of weeks of pregnancy.
These patterns were seen across several racial and ethnic groups, including White, Black, and Hispanic/Latino families. Similar risks were also observed among babies born to American Indian, Alaskan Native, Native Hawaiian, and Pacific Islander parents.
Babies born to Black parents faced higher risks of being born early, having low birthweight, or being smaller than expected.

Researchers analyzed data from nearly 14,000 mother-infant pairs from the ECHO Cohort. Arsenic exposures during pregnancy were estimated by combining water quality data with the residential histories of participants. No actual arsenic levels were tested for these participants.

This collaborative research was published in JAMA Network Open.

Nigra, A., et al. (2025) Public water arsenic and birth outcomes in the Environmental influences on Child Health Outcomes Cohort. JAMA Network Open. DOI: 10.1001/jamanetworkopen.2025.14084

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About ECHO
The ECHO Cohort Consortium is a research program supported by the National Institutes of Health (NIH) with the mission to enhance the health of children for generations to come. ECHO Cohort investigators study the effects of a broad range of early environmental influences on child health and development. For more information, visit echochildren.org.

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“Accelerated” Biological Age at Birth Not Linked to Behavioral and Emotional Health Outcomes in Early Childhood

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“Accelerated” Biological Age at Birth Not Linked to Behavioral and Emotional Health Outcomes in Early Childhood

Authors: Christine Ladd-Acosta, Heather Volk, 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 the study needed?

Previous studies have shown that early identification and intervention in the development of emotional and behavioral health challenges in children seems connected to better long-term health outcomes. Recently, researchers have begun looking at how epigenetic factors affect children’s biological age and health outcomes.

A molecular process known as DNA methylation, or DNAm, adds a tag to DNA to control gene expression. Researchers measure DNAm to estimate a person’s biological age and compare it with their chronological age to better understand the factors that may influence their long-term health outcomes. In this study, ECHO researchers looked at the link between biological age at birth, the time between conception and birth (chronological gestational age), and emotional and behavioral health outcomes in children.

What were the study results?

Differences between biological age at birth and chronological gestational age did not appear linked to emotional and behavioral problems in childhood. This study did not find any difference between boys and girls in terms of the effect of “accelerated” biological age on behavioral and emotional outcomes.

Footnote: Results reported here are for a single study. Other or future studies may provide new information or different results. You should always consult with a qualified healthcare provider for diagnosis and for answers to your personal questions.

What was the study's impact?

These results highlight that because biological age at birth does not seem to predict emotional or behavioral health challenges in early childhood, research should investigate how other biological factors at birth may influence neurodevelopmental health outcomes in early childhood.

Who was involved?

The study included four ECHO research sites in the United States and a total of 592 children.

What happened during the study?

Researchers calculated each child’s “biological age” by analyzing DNA samples collected at birth, and they compared this age to the child’s chronological gestational age. They then tested whether newborns who showed increased biological age relative to their chronological age (“accelerated aging”) were more likely to have emotional and behavioral problems in early childhood.

What happens next?

Future research in a larger sample might confirm these findings. The relatively small sample size of this study may have made it difficult to observe differences in behavioral or emotional outcomes based on child sex. Future research with larger samples could help investigate potential differences in the results between boys and girls.

Where can I learn more?

Access the full journal article, titled “Accelerated epigenetic age at birth and child emotional and behavioral development in early childhood: a meta-analysis of four prospective cohort studies in ECHO,” in Epigenetics.

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

Published September 10, 2023

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“Accelerated” Biological Age at Birth Not Linked to Behavioral and Emotional Health Outcomes in Early Childhood