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Low Birthweight is the percentage of live births where the infant weighed less than 2,500 grams (approximately 5 lbs., 8 oz.).
Low birthweight (LBW) represents two factors: maternal exposure to health risks and an infant’s current and future morbidity, as well as premature mortality risk. From the perspective of maternal health outcomes, LBW indicates maternal exposure to health risks in all categories of health factors, including her health behaviors, access to health care, the social and economic environment she inhabits, and environmental risks to which she is exposed. In terms of the infant’s health outcomes, LBW serves as a predictor of premature mortality and/or morbidity over the life course and for potential cognitive development problems.
Health risks are greatest for very low birthweight babies but infants born below 2,500 grams also face increased risk of morbidity and premature mortality. Low birthweight is preferred to very low birthweight in the County Health Rankings because it is a more common event, allowing for better data coverage. Although gestational age may be a better measure than low birthweight as it better accounts for a child’s neurological and physical development at birth, gestational age can be difficult to accurately ascertain, whereas birthweight is easily measured and reported.
Data on deaths and births were provided by NCHS and drawn from the National Vital Statistics System (NVSS). These data are submitted to the NVSS by the vital registration systems operated in the jurisdictions legally responsible for registering vital events (i.e., births, deaths, marriages, divorces, and fetal deaths).
County-level data are provided for counties with populations of 100,000 persons or more in CDC WONDER, and you can stratify by the age, race, or education of the mother among other variables. You may also be able to access natality data from state sources with fewer restrictions. We provide links to many states’ vital statistics data in our Finding More Data section.
Another way to access this data is through the Community Commons Health Equity Data Report. Data by race can be found for some communities. Note that you will need to login to access this report, but registation is free for all.
 Paneth NS. The problem of low birth weight. Future Child. 1995;5:19-34.
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