Low Birthweight
Birth to Age 3
Note
*: Statistically unstable
HHSA Regions: Health and Human Services Agency regions
Low birthweight is defined as under 2,500 grams.
Births with unknown birthweight were excluded from analyses. Starting in 2021, births with weight under 227 grams or greater than 8,165 grams were also excluded (improbable).
Gestation length is based on the obstetric (OB) estimate (last menstrual period (LMP), ultrasound, all perinatal factors). Births with unknown or improbable gestation lengths were classified as unknown (improbable lengths are those that likely reflect inaccuracies rather than actual gestation periods (under 17 complete weeks or 48 or more complete weeks)).
Prior to 2017, for Nativity of Mother, the foreign-born category includes U.S. territories.
The large proportion of births with unknown race/ethnicity affects the accuracy of statistics by race/ethnicity.
The large proportion of births with unknown educational attainment affects the accuracy of statistics by educational attainment.
Reporting of births that occur in other states is known to be incomplete. From 2017 to 2019, births that occurred outside California are excluded.
California county of residence was determined by geocoding starting in 2022.
*Numbers are censored and rates are not calculated when the number of events is fewer than 5 (indicated by “<5”). Interpret with caution rates calculated for fewer than 20 events since they are considered statistically unreliable.
Data not available:
Race-Ethnicity, for other in 2017-2018 and 2021-2022
Gender, for Undetermined, non-binary, or unknown in 2017-2019
Race-Ethnicity categories:
Hispanic, African American/black, Asian, Native American/Alaskan, Pacific Islander, White, Other, Two or more races, Unknown
Source:
State of California, Department of Public Health, Center for Health Statistics and Informatics, Birth Statistical Master Files and California Comprehensive Birth Files.
Prepared by: County of San Diego, Health and Human Services Agency, Public Health Services, Maternal, Child and Family Health Services (www.sdmcfhs.org), 9/20/2023.
What is the indicator?
This indicator—the percentage of infants born at low birthweight—is defined as weighing less than 2500 grams (5.5 lbs.), and very low birthweight is defined as weighing less than 1500 grams (3.3 lbs.) at birth. Both are included in this measure. These data are recorded on birth certificates and reported as part of local, state, and federal vital statistics.
Why is this important?
Low birth weight babies are 20 times more likely to die in their first year compared to those of normal weight. Preterm birth, before 37 weeks of gestation, significantly contributes to low birthweight, making these factors leading causes of infant mortality. Given neonatal intensive care, many infants born at low birthweight or preterm survive but experience short and long-term effects such as learning disabilities, vision, and hearing deficits. Individuals born at low birthweight also have higher risk for conditions such as high blood pressure, heart disease, and diabetes as adults.
What strategies can make a difference?
These evidence-based and best practices are used across the country to reduce low birthweight and preterm births:
- Educate women on the risks of alcohol, drugs, tobacco, STDs, hypertension, obesity, and diabetes, while promoting proper nutrition, exercise, and healthy weight before and during pregnancy.
- Promote early, comprehensive prenatal care to identify and manage risk factors.
- Fund smoking cessation programs, including Medi-Cal prenatal benefits, and eliminate secondhand smoke exposure.
- Provide intensive, evidence-based home visits for high-risk pregnant women.
- Educate on the importance of carrying pregnancies to 39-40 weeks and eliminate coverage for non-medically necessary elective deliveries before 39 weeks.