Low Birthweight

Percentage of live births with low birthweight (<2500 grams)

  • New Jersey State Health Assessment
  • Natality Data, National Vital Statistics System, National Center for Health Statistics
Dashboard-City Average

Why do we measure low birthweight?

Low birthweight and its complications are leading causes of death in the first year of life.1,2 Even babies born at a low birthweight who survive their infant years are more likely to experience long-term physical health problems and cognitive development challenges later in life.3

Causes of low birthweight include premature birth (born before 37 weeks) and restricted fetal growth due to maternal high blood pressure, maternal smoking or exposure to tobacco smoke, and insufficient maternal weight gain.4,5 Teen pregnancy, older maternal age, and fertility treatments that lead to multiple births are also associated with low birthweight.4,6 Environmental exposures, including those related to air pollution and water contamination, are also associated with low birthweight.4,7,8

Measuring low birthweight can also inform interventions aimed at increasing racial equity. There are significant racial and ethnic differences in low birthweight prevalence, with babies born to Black mothers more likely to have low birthweight compared to babies born to White, non-Hispanic mothers. This difference may be due to the chronic stress that Black mothers experience as a result of racism, along with other social inequalities and disparities in environmental exposures.3,9-11

How do we measure low birthweight?

This metric includes any infant who is born alive with a birthweight of less than 2,500 grams.

Strengths and Limitations

Strengths of Metric

Limitations of Metric

• Low birthweight can help us measure current infant health and future health.

• City officials can use the low birthweight measure in combination with the prenatal care and teen births metrics for a better understanding of maternal and child health and health care.

• This metric is available broken down by race and ethnicity, which can help target resources and interventions for groups that historically have been underrepresented

• The metric does not make clear what causes low birthweight in a community.

• This metric does not separate babies born at a very low birthweight (<1500 grams), who have even more severe health and mortality outcomes, from babies who weigh 1500grams to 2500 grams.2

• Race and ethnicity for this metric are derived from birth certificates, where the infant’s race is determined solely by maternal race, which may not be accurate for the child.

• Race and ethnicity data are often collected using discrete options that may not account for all or multiple identities, leading to undercounting of those who are more likely to select “other.”





Low birthweight is calculated by the following formula:

Low Birthweight Calculation

For more information on the calculation, please refer to the City Health Dashboard Technical Document.

Data Source

Estimates for this metric are from Natality Data from the National Vital Statistics System of the National Center for Health Statistics. Multi-year data are available for this metric. For more information, please refer to Using Multi-Year Data: Tips and Cautions

Years of Collection

Calculated by the Dashboard Team using data from 2020, 3 year estimate.


  1.  Matthews TJ, MacDorman MF, Thoma ME. Infant Mortality Statistics From the 2013 Period Linked Birth/Infant Death Data Set. National vital statistics reports : from the Centers for Disease Control and Prevention, National Center for Health Statistics, National Vital Statistics System. 2015;64(9):1-30.

  2. Wise PH. The anatomy of a disparity in infant mortality. Annu Rev Public Health. 2003;24:341-362.

  3. March of Dimes. Low Birthweight.

    https://www.marchofdimes.org/complications/low-birthweight.aspx. Updated October, 2014. Accessed February 22, 2018.

  4. Valero de Bernabé J, Soriano T, Albaladejo R, et al. Risk factors for low birth weight: a review. European Journal of Obstetrics & Gynecology and Reproductive Biology. 2004;116(1):3-15.

  5. Johnson CD, Jones S, Paranjothy S. Reducing low birth weight: prioritizing action to address modifiable risk factors. Journal of Public Health. 2017;39(1):122-131.

  6. Stanford JB, Simonsen SE, Baksh L. Fertility treatments and adverse perinatal outcomes in a population-based sampling of births in Florida, Maryland, and Utah: a cross-sectional study. BJOG : an international journal of obstetrics and gynaecology. 2016;123(5):718-729.

  7. Kleinman JC, Kessel SS. Racial differences in low birth weight. Trends and risk factors. The New England journal of medicine.1987;317(12):749-753.

  8. Collins JW, David RJ, Handler A, Wall S, Andes S. Very Low Birthweight in African American Infants: The Role of Maternal Exposure to Interpersonal Racial Discrimination. American Journal of Public Health. 2004;94(12):2132-2138.

  9. Collins JW, David RJ, Handler A, Wall S, Andes S. Very Low Birthweight in African American Infants: The Role of Maternal Exposure to Interpersonal Racial Discrimination. American Journal of Public Health. 05/06/accepted 2004;94(12):2132-2138.

  10. Burris HH, Hacker MR. Birth outcome racial disparities: A result of intersecting social and environmental factors. Semin Perinatol. Oct 2017;41(6):360-366. doi:10.1053/j.semperi.2017.07.002

  11. Miranda ML, Maxson P, Edwards S. Environmental contributions to disparities in pregnancy outcomes. Epidemiol Rev. 2009;31:67-83. doi:10.1093/epirev/mxp011

Last updated: July 26, 2023