What is low birth weight?

Babies that weigh less than 2,500 grams (about 5.5 pounds) at birth are considered to have ‘low birth weight.’

Multiple factors may contribute to low birth weight including: gestational age, sex, smoking during pregnancy, lack of prenatal weight gain, and social and environmental factors like poverty and air pollution. These problems may cause growth restrictions early in the pregnancy (‘early onset’) or later in the pregnancy (‘late onset’). When and why the onset occurs impacts the effect on the developing fetus, and the prognosis for the baby.

Why is birth weight important?

Low birth weight is the second leading cause of infant mortality. Low birth weight is an important measure of child well-being because it is also associated with short- and long-term health outcomes such as increased risk of delayed motor and social development, and development of cardiovascular disease later in life. Being born with low birth weight has also been linked to an increased need for health care and higher health care costs. Rates of low birth weight have increased in recent years underscoring the need for increased attention.

To learn more about the birth weight data presented here, check out our Technical Dictionary.


To learn more about low birth weight, visit the Oregon Health Authority (OHA), Public Health Division:

Please remember the following
  • OCID only includes children born in Oregon since 2001; ideally, the dataset will be expanded over time to represent all of the children in Oregon.
  • At this time, OCID is not able to report race and ethnicity data for birth weight; OCID is working to develop an overarching methodology to allow for an in-depth view into racial and ethnic disparities across all data in OCID.
  • To protect the identities of individuals, OCID only shows results for populations; where populations are too small and could risk revealing identifiable information, OCID displays the result as “Suppressed.”

For more information about the details and limitations of the data, please visit our Technical Dictionary.

Ready to explore the data?

The indicator display below provides two views:

  • A dashboard view for a structured way to look at the indicator by selecting a geography and then 1-2 other attributes; and,
  • A “sandbox” view for freely exploring the various attributes.

Please visit the About OCID and Explore OCID Population pages before exploring the data. For details on the indicator, attributes, data sources, and limitations, please visit the Technical Dictionary.


What explains any trends and disparities?

We don’t know yet. The Dashboard shows descriptive data, not causal relationships.  In depth analyses are needed to understand why disparities or trends occur.

OCID’s Governance Committee is working to set priorities for the 2020 analyses, which will examine the dynamics behind selected Dashboard indicators. Sign up below to receive OCID updates.

Suggested citation: Center for Evidence-based Policy, Oregon Health & Science University. Birth weight dashboard. Oregon Child Integrated Dataset (OCID) website. https://www.ocid-cebp.org/outcome/birth-weight/. Published June 3, 2020.

The Center for Evidence-based Policy partners with the Center for Health Systems Effectiveness, also at Oregon Health & Science University, on dashboard analytics.