This data is included as part of the Enivronmental Health Disparities Version 3.0 map. To see this map, visit our webpage. For more technical information on this map and the model used, visit our technical report (link).

Background 

Low birth weight (LBW) is a globally recognized marker for population health. Disparities in LBW show where there are disparities in maternal health. Because of these disparities, infants born to Black mothers are more likely to be LBW than infants born to white mothers. Programs like Women, Infants, and Children (WIC) support growth and nutrition to help address some of the disparities that lead to LBW.   

Risk factors associated with LBW include: 

• Nutritional status. 

• Prenatal care. 

• Stress. 

• Maternal smoking. 

• Maternal age (over 40 or under 20 years old). 

Prenatal exposure to pollution and pesticides can also increase the risk of LBW. People born with LBW are more vulnerable to pollution throughout their lives. 

Evidence 

Babies born with LBW are at risk for infant death and developing health problems later in life. These include coronary heart disease, type 2 diabetes, and asthma [1, 2, 3]. 

Exposure to air pollution [4], traffic pollution [5], and pesticides [6] are linked to LBW.  

Infants born to Black mothers are 2.4 times more likely to be LBW than infants born to white mothers [7]. Participation in WIC programs can reduce these health disparities by providing nutrition and assistance with getting prenatal care [8].  

Data source 

Washington State Department of Health, Center for Health Statistics, data from 2020-2024 birth certificates 

Methods 

This measure shows the percentage of live-born singleton (one baby) infants born with a birth weight of less than 2500 grams (about 5.5 pounds) out of all live-born singleton infants born to people living in Washington. It includes babies born in Washington and babies born elsewhere to Washington residents. 

We are only using data on singleton infants. Pregnancies with more than one baby are more likely to result in LBW infants because of physical limitations, rather than other health issues. 

Caveats 

This measure does not include people currently living in Washington who were born with LBW but were not Washington residents when they were born.

Sources 

1. Barker, D., Eriksson, J., Forsn, T., & Osmond, C. (2002). Fetal origins of adult disease: Strength of effects and biological basis. International Journal of Epidemiology, 31(6), 1235-9. 

2. Lu, M., & Halfon, C. (2003). Racial and ethnic disparities in birth outcomes: A life-course perspective. Maternal and Child Health Journal, 7(1), 13-30. 

3. Nepomnyaschy, L., & Reichman, N. (2006). Low birthweight and asthma among young urban children. American Journal of Public Health, 96(9), 1604-10. 

4. Westergaard, N., Gehring, U., Slama, R., & Pedersen, M. (2017). Ambient air pollution and low birth weight—are some women more vulnerable than others? Environment International, 104, 146-54. 

5. Ghosh, J., Wilhelm, M., Su, J., Goldberg, D., Cockburn, M., Jerrett, M., et al. (2012). Assessing the influence of traffic-related air pollution on risk of term low birth weight on the basis of land-use-based regression models and measures of air toxics. American Journal of Epidemiology, 175(12), 1262-74. 

6. Harley, K., Huen, K., Schall, R., Holland, N., Bradman, A., Barr, D., et al. (2011). Association of organophosphate pesticide exposure and paraoxonase with birth outcome in Mexican-American women. Plos One, 6(8), e23923. 

7. Ratnasiri, A., Parry, S., Arief, V.N. et al. (2018). Recent trends, risk factors, and disparities in low birth weight in California, 2005–2014: a retrospective study. Maternal Health, Neonatology, and Perinatology, 4(15). 

8. Khanani, I., Elam, J., Hearn, R., Jones, C., & Maseru, N. (2011). The Impact of Prenatal WIC Participation on Infant Mortality and Racial Disparities. American Journal of Public Health 100; S204-S209. 

Citation

Washington Tracking Network, Washington State Department of Health. Web. "Low Birth Weight". Data obtained from the Department of Health Center for Health Statistics, 2020-2024 Birth Certificate Data. Published September 2025.