ChildStats.gov—Forum on Child and Family Statistics
faces of children
Home  |  About the Forum  |  Publications  |  Data Sources  |  Help
Search

America's Children: Key National Indicators of Well-Being, 2011

Preterm Birth and Low Birthweight

Infants born preterm (less than 37 completed weeks of gestation) or with low birthweight (less than 2,500 grams or 5 lbs. 8 oz.) are at higher risk of early death and long-term health and developmental issues than infants born later in pregnancy or at higher birthweights.9, 116, 117 Many, but not all, preterm infants are also low birthweight, and vice versa. In 2008, infants born preterm accounted for two-thirds of all low birthweight infants, and over 40 percent of preterm infants were low birthweight.6 Preterm infants born at less than 34 weeks (early preterm) are at high risk for poor outcomes, including chronic health conditions, long-term disability, and death. The majority of preterm births are infants born at 34–36 weeks (late preterm). Late preterm infants are at lower risk of poor outcomes than infants born earlier but are at higher risk than infants delivered at term or later.9 Disorders related to preterm birth and low birthweight are the second leading cause of infant death in the United States.9

Indicator Health1.A: Percentage of infants born preterm and percentage of infants born with low birthweight, 1990–2009
Percentage of infants born preterm and percentage of infants born with low birthweight, 1990–2009

NOTE: Data for 2009 are preliminary. Late preterm infants are born at 34–36 weeks of gestation; early preterm infants are born at less than 34 weeks of gestation. Moderately low birthweight infants weigh 1,500–2,499 grams at birth; very low birthweight infants weigh less than 1,500 grams at birth.

SOURCE: National Center for Health Statistics, National Vital Statistics System.

  • The percentage of infants born preterm declined for the third straight year in 2009, to 12.2 percent, down from a high of 12.8 percent in 2006. The percentage of infants born with low birthweight did not change between 2008 and 2009; in both years it remained at 8.2 percent, down from 8.3 percent in 2006.
  • The percentage of infants born preterm had been on the rise for several decades. From 1990 to 2006, the percentage of preterm births rose from 10.6 to 12.8 percent. The increase in late preterm births (from 7.3 to 9.1 percent) accounted for most of this change. The percentage of births that were early preterm rose from 3.3 to 3.7 percent over this period.
  • The percentage of infants born with low birthweight rose from 7.0 percent of all births in 1990 to 8.3 percent in 2006. In 2009, 1.5 percent of infants were very low birthweight, up from 1.3 percent in 1990. The percentage of moderately low birthweight infants rose from 5.7 percent in 1990 to 6.8 percent in 2006, but declined to 6.7 percent in 2007 and remained there in 2008 and 2009.
  • The increasing multiple birth rate was a contributing factor to the rise in preterm birth and low birthweight between 1990 and 2006. However, both the percentage of preterm births and low birthweight infants rose substantially among singleton births as well.118 Since 2006, declines in singleton preterm birth and low birthweight rates are similar to those for all preterm and low birthweight births.

Indicator Health1.B: Percentage of infants born with low birthweight by race and Hispanic origin of mother, 1990, 2006, and 2009
Percentage of infants born with low birthweight by race and Hispanic origin of mother, 1990, 2006, and 2009

NOTE: Data for 2009 are preliminary. Race refers to mother's race. The 1977 Office of Management and Budget (OMB) Standards for Data on Race and Ethnicity were used to classify persons into one of the following four racial groups: White, Black, American Indian or Alaskan Native, or Asian or Pacific Islander. Although state reporting of birth certificate data is transitioning to comply with the 1997 OMB standard for race and ethnicity statistics, 2006 and 2009 data from states reporting multiple races were bridged to the single-race categories of the 1977 OMB standards for comparability with other states. Data on race and Hispanic origin are collected and reported separately. Persons of Hispanic origin may be of any race.

SOURCE: National Center for Health Statistics, National Vital Statistics System.

  • The percentage of Black, non-Hispanic infants born with low birthweight was higher than that of other racial or ethnic groups. The Black, non-Hispanic percentage was 13.3 in 1990, declined to a low of 13.1 percent in 1996 and 1997, rose to 14.0 percent in 2006, and declined to 13.6 percent in 2009. Among White, non-Hispanic infants, the percentage of low birthweight infants rose from 5.6 percent in 1990 to 7.3 percent in 2006, and it was 7.2 percent in 2009. The percentage of low birthweight Hispanic infants rose between 1990 and 2006 (from 6.1 to 7.0 percent), and it was 6.9 percent in 2009.
  • Between 1990 and 2006, low birthweight percentages increased for American Indian or Alaskan Native infants (from 6.1 to 7.5 percent) and Asian or Pacific Islander infants (from 6.5 to 8.1 percent). In 2009, 7.3 percent of American Indian or Alaskan Native infants were low birthweight, which was not significantly different from the percentages in 2006, 2007, or 2008. The percentage of Asian or Pacific Islander infants who were low birthweight increased from 8.1 percent in 2006 to 8.3 percent in 2009.
  • In 2009, as in earlier years, a higher percentage of Black, non-Hispanic infants were born preterm (18 percent), compared with White, non-Hispanic (11 percent) and Hispanic (12 percent) infants.
  • The percentage of Black, non-Hispanic infants born preterm declined from 19.0 percent in 1991 to 17.4 percent in 2000, rose to 18.5 percent in 2006, and declined from 18.3 percent in 2007 to 17.5 percent in 2009. From 1990 to 2006, the percentage of preterm births increased steadily for White, non-Hispanic infants (from 8.5 to 11.7 percent), then declined from 2007 to 2009 (reaching 10.9 percent in 2009). The percentage of preterm Hispanic infants increased from 11.0 to 12.3 percent between 1990 and 2007 but declined to 12.0 in 2009.

table icon HEALTH1.A HTML Table, HEALTH1.B HTML Table

9 Mathews, T.J., and MacDorman, M.F. (2010). Infant mortality statistics from the 2006 period linked birth/infant death data set. National Vital Statistics Reports, 58(17). Hyattsville, MD: National Center for Health Statistics.

116 Institute of Medicine, Committee on Understanding Premature Birth and Assuring Healthy Outcomes and Board on Health Sciences Policy. (2005). Preterm birth: Causes, consequences, and prevention. Washington, DC: The National Academies Press.

117 Hack, M., Taylor, H.G., Droter, D., Schluchter, M., Cartar, L., Andreias, L., Wilson-Costello, D., and Klein, N. (2005). Chronic conditions, functional limitations, and special health care needs of school-aged children born with extremely low birthweight in the 1990s. Journal of the American Medical Association, 294: 318–325.

118 Martin, J.A., Hamilton, B.E., Sutton, P.D., Ventura, S.J., Menacker, F.J., Kirmeyer, S., and Mathews, T.J. (2010). Births: Final data for 2006. National Vital Statistics Reports 57 (7). Hyattsville, MD: National Center for Health Statistics.