vvEPA

Indicators of Environmental Health Disparities:
Underweight and Pre-Term Births

About the Indicators of Environmental Health Disparities

EPA's indicators of environmental health disparities aim to illustrate disparities in key environmental and
public health conditions across race/ethnicity and socioeconomic status, as well as the relationship
between these health outcomes and the work of EPA programs. This project was created in direct
response to EPA's 2022-2026 Strategic Plan. These indicators are intended solely as an informational tool
and are not intended to be the basis for agency decision making. EPA does not, consistent with
applicable laws, distribute governmental benefits or burdens based on race, color, national origin, or sex.

Background Information

Preterm births are defined as a live birth before 37 weeks of gestation. Birth weight, which is impacted
by the length of gestation and fetal growth, is considered low when infants weigh less than 51 bs and 8
ounces. Preterm birth and low birth weight are associated with a range of health issues for children,
including breathing problems, feeding difficulties, developmental delay, hearing and vision problems,
and more.1 There are many potential causes for adverse birth outcomes, including maternal health
conditions and lifestyle factors.2 The role that exposure to environmental contaminants plays in adverse
birth outcomes is not yet fully understood, particularly in the potential causation of preterm birth and
low birth weight.3

Various exposures have been implicated as risk factors for full-term low birth weight, including maternal
exposure to lead and exposure to toxic substances in air, water or food.4 Research suggests that
exposure to PM2.5, carbon monoxide, and nitrogen oxides might contribute to preterm birth and low
birth weight.5,6,7 Exposure to lead is also known to cause reduced fetal growth and may cause preterm
birth.8 Preterm and low birth weight infants have a higher risk of health issues and mortality from
childhood to adulthood.3 The EPA is leading research to better understand the relationship between
exposure to environmental contaminants and adverse birth outcomes.9

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Figure 1. Low-weight Births by Race and Ethnicity

Percent

L	i	Li	

NCHS changes
gestational period
standard





>¦' .J		 m m m m m m mm m m m .m JV







Non-Hispanic Black or
African American
5.3%

I Non-Hispanic Asian
3.9%

| Other Hispanic
2.6%

I Mexican or Mexican
American
2.3%

| Non-Hispanic
American Indian or
Alaska Native
2.3%

| Non-Hispanic White
2.1%

1995 2000

2005

2010

2015

2020 '22

Data Note: Beginning in 2014, NCHS changed the standard for gestational
period from the Last Menstrual Period (LMP) based gestational age to the
Obstetric/clinical Estimate (OE) based gestational age. Refer to Measuring
Gestational Age in Vital Statistics Data: Transitioning to the Obstetric
Estimate for more information.

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Figure 2. Pre-term Births by Race and Ethnicity

Percent

15

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6

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Data Note: Beginning in 2014, NCHS changed the standard for gestational
period from the Last Menstrual Period (LMP) based gestational age to the
Obstetric/clinical Estimate (OE) based gestational age. Refer to Measuring
Gestational Age in Vital Statistics Data: Transitioning to the Obstetric
Estimate for more information.

1995 2000	2005	2010	2015	2020 '22

NCHSchanges
gestational period
standard

| Mexican or Mexican
American
8.6%

| Other Hispanic
8.6%

| Non-Hispanic Asian
7.9%

| Non-Hispanic White
7.7%

Non-Hispanic Black or
African American
12.3%

I Non-Hispanic
American Indian or
Alaska Native
11.0%

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Figure 3. Disparities in Low-weight Births by Race and Ethnicity

Percent

NCHSchanges
gestational period
standard

Non-Hispanic Black or
African American
5.3%

| Overall average*
2.8%

All other races and
ethnicities

1995

2000

2005

2010

2015

2020 '22

Data Note: Beginning in 2014, NCHS changed the standard for gestational
period from the Last Menstrual Period (LMP) based gestational age to the
Obstetric/clinical Estimate (OE) based gestational age. Refer to Measuring
Gestational Age in Vital Statistics Data: Transitioning to the Obstetric
Estimate for more information.

The "overall average" line includes other racial and ethnic groups not
shown in the other charts.

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Figure 4. Disparities iri Pre-term Births by Race and Ethnicity

Percent

18

NCHS changes
gestational period
standard

Non-Hispanic Black or
African American
12.3%

| Overall average*

8.6%

All other races and
ethnicities

1995

2000

2005

2010

2015

2020 '22

Data Note: Beginning in 2014, NCHS changed the standard for gestational
period from the Last Menstrual Period (LMP) based gestational age to the
Obstetric/clinical Estimate (OE) based gestational age. Refer to Measuring
Gestational Age in Vital Statistics Data: Transitioning to the Obstetric
Estimate for more information.

The "overall average" line includes other racial and ethnic groups not
shown in the other charts.

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What these charts show

These charts show the percent of full-term births in the United States that are low weight and the
percent of births in the United States that are pre-term from 1995 to 2022.

•	In 2022, the total percentage of full-term births that were low weight across all populations was
2.8% (Figure 3). This number varied distinctly between racial and ethnic populations, however,
with Non-Hispanic Black or African Americans experiencing the highest levels of low birth weight
during the entirety of this period.

•	In 2022, the percent of full-term births that were low weight in non-Hispanic Black or African
Americans reached its apex of 5.3% during this time period (Figure 1). This was followed by non-
Hispanic Asians (3.9%), other Hispanic (2.6%), Mexican or Mexican Americans (2.3%), non-
Hispanic American Indian or Alaska Natives (2.3%), and non-Hispanic whites (2.1%) (Figure 1).

•	Between 1995 to 2014, the percent of full-term births in the U.S. that were low weight remained
relatively stable, before realigning downward to a new baseline in 2014 as a result of the change
in the standard for determining gestational age (described below). Since 2014, these
percentages have been increasing (Figure 1).

•	In 2022, the total percent of births that were pre-term were 8.6% (Figure 4). This number varied
by race and ethnicity, with the highest rates experienced by the non-Hispanic Black population,
which had a pre-term birth percentage of 12.3% in 2022 (Figure 2). Other percentages of pre-
term births for different racial and ethnic groups include non-Hispanic American Indian or Alaska
Native at 11.0%, Mexican or Mexican American at 8.6%, other Hispanic at 8.6%, non-Hispanic
Asian at 7.9%, and non-Hispanic white at 7.7% (Figure 2).

These charts make note of a change to the National Center for Health Statistics (NCHS) standard for
determining gestational age. Prior to 2014 gestational age was measured based on maternal reporting of
the Last Menstrual Period (LMP). Since 2014, the new more accurate Obstetric Estimate (OE) has been
used for reporting.

This data was reported to the National Vital Statistics System (NVSS). The NVSS compilation of this data is
the result of the cooperation between the Centers for Disease Control and Prevention's (CDC's) National
Center for Health Statistics (NCHS) and 57 vital registration jurisdictions (50 states, New York City, the
District of Columbia, and five territories) to provide access to statistical information from birth
certificates.10

What these charts do not show

These charts do not demonstrate why there are higher rates of adverse birth outcomes for certain racial
and ethnic groups. While analyzing the number of cases by racial and ethnic groups is useful for
determining those who may be most vulnerable and impacted by adverse birth outcomes, these graphs
do not suggest that race and ethnicity themselves cause these outcomes. Factors include maternal
cigarette smoking, maternal alcohol and drug use, maternal weight at conception, pregnancy-induced
hypertension and pre-eclampsia, being the first-born, congenital anomalies, and other genetic factors.5
While differences in socioeconomic status and other risk factors are known to impact birth outcomes,
studies that have controlled for these variables still find differences between white women and women
of color.1115

Relevant EPA Activities

Offices across the EPA are engaged in activities to reduce exposure to environmental contaminants in
utero and early in life, including the following:

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•	Regulating criteria air pollutants and their precursors: Under the Clean Air Act, the EPA sets the
National Ambient Air Quality Standards (NAAQS) for criteria air pollutants and works with state
and local air quality management agencies to meet those standards. In 2024, the EPA
strengthened the NAAQS for particulate matter below 2.5 micrometers in diameter (PM2.5) from
12.0 to 9.0 micrograms per cubic meter as the primary annual standard, continuing to protect
Americans from harmful levels of pollution. The EPA also sets, reviews, and implements
standards for lead pollution. For further information about the enforcement of these
regulations, see EPA's webpage on Air Enforcement.

•	Reducing lead exposure: Offices across EPA are engaged in activities to reduce lead exposure. In
October 2024, EPA announced the finalized improvements to the Lead and Copper Rule to better
protect communities from lead in drinking water. The proposed rule would require the vast
majority of water systems to replace lead service lines in the U.S. within 10 years. EPA is also
investing $15 billion through the Bipartisan Infrastructure Law to identify and replace lead
service lines around the nation. The Bipartisan Infrastructure Law also dedicates $11.7 billion to
projects that improve drinking water quality, including reducing lead in drinking water. To
address lead in air pollution, EPA is now working on proposing and promoting regulatory
standards to address lead emissions from aircraft engines under the Clean Air Act. The EPA also
released the Environmental Justice Toolkit for Lead Paint Enforcement Programs to help address
toxic lead exposure in communities, especially those with high levels of lead pollution. Finally,
EPA is taking steps to improve both Superfund and Brownfields sites to reduce lead exposure at
contaminated properties.

For further information on indicators related to environmental and human health, explore EPA's Report
on the Environment, and for further information on indicators related to children's environmental health,
explore EPA's America's Children and the Environment (ACE) report.

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References

1)	CDC. Preterm Birth. Last updated May 15, 2024. Accessed November 4, 2024. Preterm Birth I
Maternal Infant Health I CDC

2)	CDC. National Environmental Public Health Tracking: Reproductive and birth outcomes. Last
updated October 26, 2016. Accessed June 22, 2024.
https://ephtracking.cdc.gov/showRbPrematureBirthEnv.action.

3)	U.S. EPA. Health - Adverse Birth Outcomes. Published October 9, 2023. Accessed June 10, 2024.
https://www.epa.gov/americaschildrenenvironment/health-adverse-birth-outcomes

4)	NCHS. 2019. National Vital Statistics System improvements fact sheet. March 2019.
https://www.cdc.gov/nchs/data/factsheets/factsheet-nvss-improvements-H.pdf (PDF).

5)	U.S. EPA. Integrated Science Assessment for Particulate Matter. Published March 7, 2017.
Accessed June 27, 2024. Integrated Science Assessment (ISA) for Particulate Matter (Final
Report. Dec 2019) I Integrated Science Assessments I Environmental Assessment I US EPA

6)	U.S. EPA. Integrated Science Assessment for Oxides of Nitrogen. Published January 2016.
Accessed June 27, 2024. Integrated Science Assessment (ISA) for Oxides of Nitrogen - Health
Criteria (Final Report. Jan 2016) I Integrated Science Assessments I Environmental Assessment I
US EPA

7)	U.S. EPA. Integrated Science Assessment for Carbon Monoxide. Published January 2010.

Accessed June 27, 2024. Integrated Science Assessment (ISA) for Carbon Monoxide (Final Report.
Jan 2010) I Integrated Science Assessments I Environmental Assessment I US EPA

8)	U.S. EPA. Integrated Science Assessment for Lead. Published January 2024. Accessed November
27, 2024. Integrated Science Assessment (ISA) for Lead (Final Report) I Integrated Science
Assessments I Environmental Assessment I US EPA

9)	U.S EPA. Children's Health Research regarding Pre-term Birth, Low Birth Weight, Birth Defects
and Infant Mortality. Published July 18, 2023. Accessed June 10, 2024.

https://www.epa.gov/children/childrens-health-research-regarding-pre-term-birth-low-birth-
weight-birth-defects-and.

10)	NCHS. 2019. National Vital Statistics System improvements fact sheet. March 2019.
https://www.cdc.gov/nchs/data/factsheets/factsheet-nvss-improvements-H.pdf (PDF).

11)	CDC. Preterm Birth. Last updated May 15, 2024. Accessed November 4, 2024. Preterm Birth I
Maternal Infant Health I CDC

12)	Johnson, J. D., Green, C. A., Vladutiu, C. J., & Manuck, T. A. (2020). Racial disparities in
prematurity persist among women of high socioeconomic status. American Journal of Obstetrics
& Gynecology MFM, 2(3), 100104. https://doi.Org/10.1016/j.ajogmf.2020.100104

13)	Burris, H. H., & Hacker, M. R. (2017). Birth outcome racial disparities: A result of intersecting
social and environmental factors. Seminars in Perinatology, 41(6), 360-366.
https://doi.Org/10.1053/j.semperi.2017.07.002

14)	Almeida, J., Becares, L., Erbetta, K., Bettegowda, V. R., & Ahluwalia, I. B. (2018). Racial/Ethnic
Inequities in Low Birth Weight and Preterm Birth: The Role of Multiple Forms of Stress. Maternal
and Child Health Journal, 22(8), 1154-1163. https://doi.org/10.1007/sl0995-018-2500-7

15)	Fishman, S. H., Hummer, R. A., Sierra, G., Hargrove, T., Powers, D. A., & Rogers, R. G. (2020).
Race/ethnicity, maternal educational attainment, and infant mortality in the United States.
Biodemography and Social Biology, 66(1), 1-26.
https://doi.org/10.1080/19485565.2020.1793659

United States Environmental Protection Agency	EPA 231R24004

1200 Pennsylvania Avenue, NW	December 2024

Washington, DC 20460	www.epa.gov

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