Low birthweight (less than 5.5 pounds) is strongly associated with poor developmental outcomes, beginning in infancy but extending into adult life. Low weight is often associated with pre-term delivery, but can occur also with full-term births. Research points to a number of factors that can contribute to the likelihood of low weight at birth, including smoking during pregnancy; low weight gain during pregnancy, or low pre-pregnancy weight; and the pregnant parent’s stress during pregnancy. The National Center for Health Statistics defines low birth weight as a weight of less than 2,500 grams, or 5 pounds and 8 ounces.
Data for the State of Babies Yearbook: 2023 were calculated using data from CDC Wonder. The numerator is the number of infants born with low birth weight, which is defined by the CDC as less than 2,500 grams, or 5.5 pounds. The denominator is the total number of infants whose birth weights are known.
This indicator can be disaggregated by race/ethnicity and urbanicity. Race/ethnicity: CDC Wonder contains very detailed information on the pregnant parent’s race/ethnicity. After examining sample sizes, we are presenting the following subgroups: non-Hispanic American Indian and Alaska Native, non-Hispanic Asian, non-Hispanic Black, non-Hispanic more than one race, non-Hispanic Native Hawaiian or other Pacific Islander, non-Hispanic White, and Hispanic of all races. Births where the origin of the mother was unknown were included with non-Hispanic births in the CDC Wonder data. Urbanicity: CDC Wonder classifies the pregnant parent as living in a metro (urban) or non-metro (rural) area according to 2013 designations. The metro group includes counties in these categories: large central metro, large fringe metro, medium metro, and small metro. The non-metro group includes counties in these categories: micropolitan (non-metro) and noncore (non-metro). For the subgroups, the total/national average is out of states whose data is presented for that subgroup, rather than all states. Reichman, N. (2005). Low birth weight and school readiness. In School readiness: Closing racial and ethnic gaps. The Future of Children, 15(1), 91-116. https://doi.org/10.1353/foc.2005.0008; Ricketts, S. A., Murray, E. K., & Schwalberg, R. (2005). Reducing low birthweight by resolving risks: Results from Colorado’s Prenatal Plus Program. American Journal Public Health, 57(11),1952-1957. https://doi.org/10.2105/AJPH.2004.047068
Source:
Centers for Disease Control and Prevention, National Center for Health Statistics. (2022). About Natality, 2016-2020 expanded. http://wonder.cdc.gov/natality-expanded-current.html