Women Pregnant During COVID-19 Pandemic Experienced More Stress, Depression Symptoms

Authors: Alison E. Hipwell, Irene Tung, 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.

What were the study results?

This study compared ECHO participants who were pregnant during the COVID-19 pandemic with participants who were pregnant before the pandemic. Participants who were pregnant during the pandemic reported more stress and symptoms of depression. Lower levels of physical activity were associated with more distress, and higher levels of emotional support were associated with less distress during pregnancy for both groups. The results also showed that pregnancies during the pandemic were slightly shorter on average but there was no impact on infant birth weight.

What was the study's impact?

This study highlights the importance of providing access to emotional support and mental health care during pregnancy and identifying ways to promote physical activity to help improve maternal health and well-being, regardless of external conditions like the pandemic.

Why was this study needed?

Previous studies on the effects of the COVID-19 pandemic on pregnancy outcomes have been mixed. This is partly because background information about pregnant participants has been missing and partly because the effects of the pandemic are different for different populations across the country. This study involved pregnant participants from across the United States and collected information about their mental health and well-being along with data on their pregnancy outcomes. The study also focused on positive factors that can be used to improve pregnancy health and birth outcomes, such as physical activity and emotional support.

Who was involved?

This study included 501 pregnant participants who gave birth during the COVID-19 pandemic (between March 12, 2020 and May 30, 2021) and 501 pregnant participants who gave birth before the pandemic (prior to March 11, 2020). Participants were 31 years old on average and enrolled in one of 16 ECHO research sites across the United States.

What happened during the study?

Participants answered questions about their experiences with stress and depression, reported on their physical activity, and described the emotional support they received during pregnancy. The researchers also collected information on participants’ birth outcomes from medical records and maternal reports.

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?

More research is needed to understand how social support and physical activity during pregnancy may protect pregnant women from stress or depression during difficult times. Future research may look for more details about the types of experiences during the COVID-19 pandemic that had the most influence on pregnancy health and well-being.

Where can I learn more?

Access the full journal article, titled “Impact of Sedentary Behavior and Emotional Support on Prenatal Psychological Distress and Birth Outcomes During the COVID-19 Pandemic,” 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 8, 2023

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Women Pregnant During COVID-19 Pandemic Experienced More Stress, Depression Symptoms

Pregnancy Complications Like Preeclampsia and Gestational Diabetes May Be Linked to Slower Biological Development in Babies

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Pregnancy Complications Like Preeclampsia and Gestational Diabetes May Be Linked to Slower Biological Development in Babies

Authors: Carrie Breton, Christine Ladd-Acosta, et al.

Who sponsored this study?

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

What were the study results?

The researchers found that babies who were exposed to preeclampsia or gestational diabetes while they were developing in the womb were biologically younger than babies without those exposures, indicating that these exposures may have slowed down babies’ biological development. This difference was more noticeable in female babies compared to male babies.

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 was the study's impact?

In this study, researchers found that certain pregnancy complications are related to slower biological development at birth, with girls being more affected than boys. These results provide an important clue about how pregnancy complications can affect underlying biological processes in newborn infants, as preeclampsia and gestational diabetes have been linked to child health outcomes.

Why was the study needed?

Preeclampsia (high blood pressure that can cause kidney or other organ damage during pregnancy) and gestational diabetes (high blood sugar during pregnancy) have been linked to a number of birth complications and children’s health outcomes, including birth weight. More research is needed to identify the biological processes in newborn babies that are affected by these pregnancy complications so doctors can use that information to provide treatments to improve children’s health. This study evaluated how pregnancy complications affect newborn infant’s epigenetic age, a measure of their “biological age” based on molecular markers in their cells.

Who was involved?

The study included 1,801 children from 12 ECHO cohorts across the United States. The participants were born between 1998 and 2008 to mothers who had preeclampsia or gestational diabetes during pregnancy.

What happened during the study?

ECHO researchers calculated each infant’s biological age by analyzing DNA samples collected at birth and compared their biological age (epigenetic age) to their chronological age at birth (measured in pregnancy weeks). Then, the researchers compared the biological ages of newborns exposed to pregnancy complications to the biological ages of babies who were not exposed.

What happens next?

The researchers will continue this research with a larger number of participants. They also plan to see whether the same biological changes detected at birth are related to health outcomes later in childhood.

Where can I learn more?

Access the full journal article, titled “Analysis of Pregnancy Complications and Epigenetic Gestational Age of Newborns,” 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 February 24, 2023

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Pregnancy Complications Like Preeclampsia and Gestational Diabetes May Be Linked to Slower Biological Development in Babies

ECHO Researchers Investigate Whether Prenatal Chemical Exposures Affect the Development of Autism-related Traits in Children

Posted on January 26, 2023October 25, 2024 by Jodi Snare

Collaborative ECHO research led by Jennifer Ames, PhD of the Kaiser Permanente Northern California Division of Research and Ghassan Hamra, PhD of Johns Hopkins Bloomberg School of Public Health, investigates whether exposures to per- and polyfluoroalkyl substances (PFAS) during pregnancy were associated with the development of autism-related traits in children. The researchers looked at data from 1,224 mother-child pairs and found that prenatal exposure to one specific PFAS chemical, perfluorononanoic acid (PFNA), may be associated with an increase in autism-related traits in children. Prenatal exposure to the mixture of all PFAS chemicals combined was not associated with increased autism-related traits in children. This research, titled “Prenatal exposure to per- and polyfluoroalkyl substances and childhood autism-related outcomes,” is published in Epidemiology.

PFAS are widely used, long lasting chemicals, the components of which break down very slowly over time. Previous studies that have investigated the association between prenatal PFAS exposure and childhood autism spectrum disorder (ASD) have been inconsistent and mostly involved small sample sizes. This study leveraged the large, diverse ECHO-wide cohort to evaluate how prenatal PFAS exposure affects the development autism-related traits, even when a child does not receive a clinical ASD diagnosis.

This study included children born between 2011 and 2018 from 10 racially and ethnically diverse ECHO cohorts across the United States, including one cohort that enrolls children from families with an increased likelihood of ASD. The researchers measured the levels of eight different PFAS in blood samples collected from mothers during pregnancy. Later, when their children were aged 2.5 years or older, researchers asked caregivers to report on their child’s autism-related traits using a questionnaire called the Social Responsiveness Scale (SRS). The research team tracked the associations between these data to examine child SRS scores in relation to each individual PFAS as well as the combination of the PFAS.

“In the U.S. population, exposures to perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have dropped substantially since the industry voluntarily phased out these chemicals in the early 2000s,” said Dr. Ames. “However, other PFAS exposures have increased over time, including thousands with unknown toxicity. These so-called ‘forever chemicals’ continue to pose risks to health even after they are phased out because they persist in the environment and inside people’s bodies and don’t break down easily.”

These results underscore the need for more research on whether PFAS chemicals might have more significant effects on child neurodevelopment, and whether factors such as genetics, underlying health conditions, or nutritional status may change the effect of PFAS exposure on brain development.

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ECHO Study Suggests Eating Processed Foods May Affect How Long Mothers Breastfeed Their Babies

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ECHO Study Suggests Eating Processed Foods May Affect How Long Mothers Breastfeed Their Babies

Authors: Emily Zimmerman, et al.

Who sponsored this study?

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

What were the study results?

The results from this study suggested that pregnant women who reported eating the most processed food and take-out tended to breastfeed for an average of 16 weeks (4 months), while pregnant women who reported eating the least amount of processed food and take-out breastfed for an average of 41 weeks (10 months).

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 was the study's impact?

This is the first large and diverse cohort study examining the potential link between maternal food quality during pregnancy and breastfeeding duration. The results from this study suggest that pregnant women who eat a lot of processed food or take-out during pregnancy, tend to breastfeed for a shorter period of time.

Why was this study needed?

Breastfeeding promotes positive health outcomes for infants, but few studies have looked at the connection between the quality of mothers’ food during pregnancy and the length of time they breastfed. This study examined the relationship between self-reported food quality and preparation (e.g., organic foods, processed foods, take out) during pregnancy and breastfeeding duration.

Who was involved?

This study included 751 mothers who were at least 18 years old and their infants from 12 ECHO cohorts located across the United States.

What happened during the study?

Mothers reported on their food source and preparation during pregnancy and were placed in one of three groups: high, moderate, or low food source quality. Mothers also reported on their breastfeeding duration. Researchers investigated whether there was a relationship between the mothers’ food quality during pregnancy and the length of time they breastfed.

What happens next?

Future studies are needed to understand the relation between breastfeeding duration and maternal food quality over time. These studies can also provide more specific information on maternal diet, food source, and preparation during pregnancy while considering other important factors, like socioeconomic status, that may affect the types of foods mothers have access too.

Where can I learn more?

Access the full journal article, titled “Association Between Quality of Maternal Prenatal Food Source and Preparation and Breastfeeding Duration in The Environmental influences on Child Health Outcome (ECHO) Program,” in Nutrients.

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

Published November 21, 2022

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ECHO Study Suggests Eating Processed Foods May Affect How Long Mothers Breastfeed Their Babies

ECHO Study Suggests Oxidative Stress Contributes to Mother’s Risk for Preterm Birth

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ECHO Study Suggests Oxidative Stress Contributes to Mother's Risk for Preterm Birth

Authors: Stephanie Eick, Rachel Morello-Frosch, et al.

Who sponsored this study?

Research reported in this publication was supported by the Environmental influences on Child Health Outcomes (ECHO) Program, Office of The Director, National Institutes of Health (NIH).

What were the study results?

Pregnant participants who had higher levels of oxidative stress biomarkers during pregnancy were more likely to deliver preterm babies. This association was stronger for participants who experienced preterm birth that was sudden and unexpected or occurred prior to 34 weeks.

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 was the study's impact?

This study is the largest to date to look at the relationship between oxidative stress and preterm birth.

The study included a large group of racially, ethnically, and demographically diverse pregnant participants from across the mainland United States and Puerto Rico. The results from this study support prior findings that oxidative stress is higher among pregnant women who deliver preterm. The methods used in this study may help doctors identify pregnant women who may be at risk for preterm birth and plan targeted interventions.

Why was this study needed?

Oxidative stress is a process that can trigger cell damage and can play a role in the development of some diseases. Previous research has shown that oxidative stress in pregnant women may be linked to preterm birth. However, prior studies on this topic have involved small, primarily White populations, which does not reflect the diversity in the United States.

Who was involved?

This study involved 1,916 pregnant participants in the United States and Puerto Rico who were enrolled in one of four ECHO cohorts.

What happened during the study?

The researchers measured the levels of oxidative stress biomarkers from urine samples collected from participants during the second and third trimesters of pregnancy. They used these measurements to determine whether levels of oxidative stress were higher among participants who delivered their babies before 37 weeks (preterm birth).

What happens next?

Next, the researchers will study how exposure to environmental chemicals may lead to an increase in oxidative stress, ultimately leading to preterm birth. Future research will also identify what risk factors lead to higher oxidative stress during pregnancy.

Where can I learn more?

Access the full journal article, titled “A pooled analysis of four birth cohorts examining urinary oxidative stress biomarkers and preterm birth” in the American Journal of Obstetrics and Gynecology.

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

Published November 15, 2022

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ECHO Study Suggests Oxidative Stress Contributes to Mother's Risk for Preterm Birth

ECHO Study Identifies Depression, Anxiety, and Other Drug Use as Risk Factors for Opioid Use During Pregnancy

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ECHO Study Identifies Depression, Anxiety, and Other Drug Use as Risk Factors for Opioid Use During Pregnancy

Authors: Ruby H.N. Nguyen, Monica McGrath, et al.

Who sponsored this study?

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

What were the study results?

Most of the participants who used opioids were non-Hispanic White and had at least some college education. Opioid use was more common among people who used tobacco or illegal drugs, and those with a history of depression or anxiety. Additionally, opioid use during pregnancy in this study was rare—only 2.8% of participants used opioids during pregnancy, and the majority of opioid use originated from a prescription.

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 was the study's impact?

This is among the largest observational studies of opioid use during pregnancy thus far, and the diverse sample of pregnant participants is more representative of the U.S. population than previous studies. Results from this study strengthened evidence about the co-occurrence of opioid use in pregnancy with depression and use of multiple substances (such as tobacco and illegal drugs). These findings will help to inform further research on screening tools for opioid use during pregnancy. Additionally, the finding that most opioid use originated from prescriptions reinforces the need to reduce the amount of circulating prescription drugs and to better monitor over-prescription of opioids to pregnant women and provide them with alternative treatment solutions for pain management and opioid dependency.

Why was this study needed?

Opioids are a class of drugs used as prescription pain relievers that can cause dependence or addiction. The opioid crisis has disproportionately affected women, and use of these drugs can have detrimental effects on women of reproductive ages and on developing fetuses. Previous studies of opioid use during pregnancy have been limited to individuals in specific geographic locations or those with specific types of insurance. The stigmatization of this population has also complicated the collection of data on maternal opioid use during pregnancy. Using a large sample size, this study examined opioid use in a diverse population of pregnant women across the United States to investigate rare exposures – such as polysubstance use - and characteristics associated with opioid use during pregnancy.

Who was involved?

This study included over 20,000 pregnant participants from 32 ECHO cohorts across the U.S., creating a large and geographically diverse sample.

What happened during the study?

The researchers gathered data from pregnant women who were already participants in ECHO cohorts between 1991 and 2021. Medical records, laboratory tests, and self-reports were used to assess opioid use and potentially related factors, such as demographics, use of other substances, and history of anxiety or depression.

What happens next?

This study shows that further research is needed on the factors that may lead to use of multiple substances during pregnancy and the association between substance use and depression. This research can help inform the development of screening tools and procedures for identifying individuals who are potentially at risk for opioid use during pregnancy.

Where can I learn more?

Access the full journal article, titled “Characteristics of Individuals in the U.S. who Used Opioids during Pregnancy,” in the Journal of Women’s 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 9, 2022

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ECHO Study Identifies Depression, Anxiety, and Other Drug Use as Risk Factors for Opioid Use During Pregnancy

Diabetes and Depression During Pregnancy May Be Linked to Higher Risk of Postpartum Depression in Mothers

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Diabetes and Depression During Pregnancy May Be Linked to Higher Risk of Postpartum Depression in Mothers

Author(s): Lauren Shuffrey, et al.

Who sponsored this study?

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

What were the study results?

The study found that participants with gestational diabetes were more likely to be classified as having prenatal depression compared to those without gestational diabetes. Participants with both gestational diabetes and prenatal depression had an increased risk of developing postpartum depression. But gestational diabetes on its own, without prenatal maternal depression, was not linked to an increased risk of postpartum depression.

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 was the study's impact?

These findings underscore the importance of universal depression screenings during pregnancy and for at least a year following birth.

Why was this study needed?

There is a lack of research into how the combination of gestational diabetes (a type of diabetes that develops during pregnancy) and prenatal depression affects a person’s risk for postpartum depression.

Who was involved?

This study included 5,822 participants from 16 ECHO cohorts across 13 U.S. states and Puerto Rico. A total of 4,606 participants had neither gestational diabetes nor prenatal depression, 416 had gestational diabetes only, 689 had prenatal maternal depression only, and 111 had both gestational diabetes and prenatal maternal depression.

What happened during the study?

Researchers collected information from the participants including gestational diabetes diagnosis and self-assessments of depression symptoms during and after pregnancy. The researchers then used that data to evaluate the relationship between gestational diabetes, prenatal depression, and postpartum depression.

What happens next?

Future studies should examine potential mechanisms underlying the relationship between gestational diabetes, prenatal depression, and postpartum depression. The ECHO Program is currently working towards analyzing blood samples collected during pregnancy to identify potential factors involved in this relationship.

Where can I learn more?

Access the full journal article, titled “Gestational Diabetes Mellitus, Prenatal Maternal Depression, and Risk for Postpartum Depression: An Environmental Influences on Child Health Outcomes (ECHO) Study” in BMC Pregnancy and Childbirth.

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

Published October 8, 2022

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Diabetes and Depression During Pregnancy May Be Linked to Higher Risk of Postpartum Depression in Mothers

ECHO Study Reveals Pregnant Women Are Exposed to Dangerous Chemicals Found in a Variety of Household Products

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ECHO Study Reveals Pregnant Women Are Exposed to Dangerous Chemicals Found in a Variety of Household Products

Authors: Giehae Choi, Jessie Buckley, Tracey Woodruff, et al.

Who sponsored this study?

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

What were the study results?

Melamine and cyanuric acid were found in over 99% of the study participants. Four types of aromatic amines were also found in nearly all pregnant participants. Levels of these chemicals were higher among Hispanic and non-Hispanic Black participants and in those exposed to tobacco smoke. For example, levels of 3,4-dichloroaniline—a chemical used in the production of dyes and pesticides—were more than 100% higher among Black and Hispanic women compared to White women.

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 was the study's impact?

This is the first national study to reveal that pregnant women in the U.S. are widely exposed to melamine, cyanuric acid, and aromatic amines—chemicals that may be harmful to maternal health and child development. This raises concerns for the health of pregnant women and babies.

Why was this study needed?

Chemicals like melamine, cyanuric acid, and aromatic amines are commonly used to make a variety of household products. Melamine can be found in dishware, plastics, flooring, kitchen counters, and pesticides. Cyanuric acid can be found in disinfectants, plastics, and swimming pools. And aromatic amines can be found in hair coloring, mascara, tattoo ink, paints, tobacco smoke, and diesel fumes. People can be exposed to these chemicals through the air, contaminated food, household dust, water, plastics, products that contain dyes and pigments, and many other sources.

Melamine was globally recognized as toxic after baby formula poisoning incidents in 2007 to 2008, which resulted in health problems in children including kidney stones, kidney failure, and in some cases, death. Research suggests that melamine may also be linked to reduced brain development. There is limited research on the effects of melamine on adults, although preliminary evidence suggests that it may be linked to cancer and other negative health outcomes. Prior studies on melamine were only conducted among pregnant women in Asian countries or limited to non-pregnant women in the U.S. Despite melamine’s potential harm and common use in household products, population-level exposure is not regularly monitored in the U.S.

Who was involved?

This study included 171 pregnant participants from nine ECHO cohorts located in California, Georgia, Illinois, New Hampshire, New York, and Puerto Rico. Of these participants, 40% were Hispanic, 34% were White, 20% were Black, 4% were Asians, and the remaining 2% were from other or multiple racial groups.

What happened during the study?

Researchers measured the levels of 45 chemicals in urine samples collected from participants during pregnancy. They used new methods to capture the levels of these chemicals in the urine samples, even those present in small amounts. Then, the researchers compared chemical levels across participants with different sociodemographic backgrounds.

What happens next?

Researchers are expanding on this study to look at the effects of higher exposures to these chemicals during pregnancy in over 1,700 pregnant participants and investigate whether these exposures are linked with child health outcomes.

Where can I learn more?

Access the full journal article, titled “Exposure to melamine and its derivatives and aromatic amines among pregnant women in the United States: The ECHO Program,” in Chemosphere.

Published August 30, 2022

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ECHO Study Reveals Pregnant Women Are Exposed to Dangerous Chemicals Found in a Variety of Household Products

ECHO Researchers Investigate Effects of Preterm Birth, Environmental Exposures on Child Health

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ECHO Researchers Investigate Effects of Preterm Birth, Environmental Exposures on Child Health

Authors: Michael O’Shea, Monica McGrath, Judy Aschner, Barry Lester, et al.

Who sponsored this study?

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

What were the study results?

ECHO researchers are collecting extensive data from very preterm infants, including data on learning and intellectual impairments, asthma, obesity, sleep health, and the effects of the COVID-19 pandemic. This article provides an overview of how data from ECHO cohorts are being used to address questions about the combined effects of preterm birth and environmental exposures on child health outcomes.

What was the study's impact?

Researchers can use the information in this review to enhance their knowledge of the ECHO Program’s resources to study preterm infants. Researchers can use ECHO data to investigate the relationship between preterm birth, environmental exposures, and childhood risk of chronic and developmental health conditions.

Why was this study needed?

Infants who are born premature (before 32 weeks of pregnancy) are at a high risk for multiple health disorders. This review paper outlines resources available within the ECHO Program for researchers seeking to study the effects of preterm birth and environmental exposures on child health outcomes.

Who was involved?

This review article includes ECHO cohorts that enrolled infants who were born premature. These cohorts enrolled almost 1,800 preterm infants across 14 states that were born between April 2002 and March 2020, including three ECHO cohorts that are almost exclusively comprised of preterm infants.

What happened during the study?

A team of experts reviewed the characteristics of the ECHO cohorts that are collecting data on preterm infants. Through this review, they sought to describe the research goals, participant selection criteria, key environmental exposures, and child health outcomes of each cohort.

What happens next?

ECHO researchers will continue to investigate early life factors and environmental exposures that may affect children’s health outcomes later in life. Researchers not participating in the ECHO Program will be able to obtain de-identified data from preterm children in the ECHO-wide Cohort, along with data from around 30,000 children born at term through a controlled-access public use database. This data will include information about a broad range of environmental exposures and outcomes related to chronic illness among children in the United States. Using this data, researchers can continue to build off of ECHO’s mission to enhance the health of children for generations to come.

Where can I learn more?

Access the full journal article, titled “Environmental influences on Child Health Outcomes: Cohorts of Individuals Born Very Preterm,” in Pediatric 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 10, 2022

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ECHO Researchers Investigate Effects of Preterm Birth, Environmental Exposures on Child Health

ECHO Study Suggests Air Pollution, Secondhand Smoke, Formaldehyde Exposure Affect Length of Time to Get Pregnant

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ECHO Study Suggests Air Pollution, Secondhand Smoke, Formaldehyde Exposure Affect Length of Time to Get Pregnant

Author(s): Eva Siegel, Linda Kahn, et al.

Who sponsored this study?

This research was supported by the Environmental influences on Child Health Outcomes (ECHO) program, the Office of the Director, the National Institutes of Health, with co-funding from the Office of Behavioral and Social Sciences Research (OBSSR).

What were the study results?

The strongest evidence points to an association between exposures to traffic-related air pollution, secondhand smoke, and a chemical called formaldehyde—a common workplace exposure in construction sites and nail salons—and longer time to pregnancy. Specifically, exposure to particulate matter and nitrogen oxide gases lowered couples’ chances of becoming pregnant. Traffic and the burning of other types of materials besides gas and diesel create particulate matter and nitrogen oxide gases. Volatile organic compounds, which are used in manufacturing processes, did not appear to affect time to pregnancy.

What was the study's impact?

This review suggests that certain chemicals in the air may lengthen the time it takes for couples to become pregnant. More research is needed to better understand how these chemicals affect reproductive health. To collect this information, future studies can provide participants with personal air monitors that can let researchers know about the quality of air participants are actually breathing instead of relying on imprecise data from outdoor monitors or participant recall.

The research team also pointed out that there are remaining questions about whether the air people breathe around the time of conception is what matters most or whether there are certain life stages, such as puberty, when being exposed to air pollution may be especially damaging. The ECHO-wide Cohort, which allows researchers to access information from a large and diverse population, can serve as an important resource for answering these questions.

Why was this study needed?

Previous studies have looked at how air pollution may affect how long it takes to become pregnant. Time to pregnancy is a measure used to estimate a couple’s ability to conceive and is commonly used to diagnose infertility. In this paper, the authors review past studies on air pollution to identify types of air pollutants—including pollution from traffic, chemicals in the workplace, and secondhand smoke—that might affect how long it takes to get pregnant.

Who was involved?

This review includes all papers published in English on this topic from January 1, 1990 to February 11, 2021. The analysis covered 33 articles, of which eight looked at outdoor air quality, six looked at secondhand smoke exposure, and 19 looked at air quality in the workplace.

What happened during the study?

The research team searched six leading science libraries and identified 33 human studies related to exposure to outdoor and indoor air pollutants and time to pregnancy. The team read each article, assigned it a score based on the quality of the study design, and created summary tables containing the most important findings of each study. They then compared the consistency of results between studies, especially among high-quality papers, about whether certain types of air pollution affected time to pregnancy.

What happens next?

This is the third review this team of authors has written on chemicals and time to pregnancy. Individual authors will continue to fill in the research gaps previously mentioned, including conducting studies where women will be wearing personal air monitors.

Where can I learn more?

Access the full journal article, titled “Indoor and outdoor air pollution and couple fecundability: a systematic review” in Human Reproduction Update.

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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Published July 27, 2022

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ECHO Study Suggests Air Pollution, Secondhand Smoke, Formaldehyde Exposure Affect Length of Time to Get Pregnant