Home | About the Forum | Publications | Data Sources | Help

America's Children: Key National Indicators of Well-Being, 2007

Low Birthweight

Low-birthweight infants (infants born weighing less than 2,500 grams, or 5 lb. 8 oz.) are at higher risk of death or long-term illness and disability than are infants of normal birthweight.^{29, 112, 113} Low birthweight results from an infant's being born preterm (before 37 weeks' gestation) or from being small for his or her gestational age.

Indicator HEALTH1: Percentage of infants born with low birthweight by mother's race and Hispanic origin, 1980–2005

NOTE: Data for 2005 are preliminary.

SOURCE: Centers for Disease Control and Prevention, National Center for Health Statistics, National Vital Statistics System.

The percentage of infants with low birthweight was 8.2 in 2005, up from 7.9 percent in 2003 and 8.1 percent in 2004, and has increased slowly but steadily since 1984 (6.7 percent). The percentage for 2005 was the highest since 1968.^{6, 10}
The percentage of Black, non- Hispanic infants with low birthweight is significantly higher than that of any other racial or ethnic group. From 1990 to 2003, the percentage of low birthweight among Black, non-Hispanic infants varied between 13.1 and 13.6 percent, but the percentage rose to 14.0 in 2005. Infants of other racial and ethnic groups also experienced increases between 1990 and 2005. Among White, non-Hispanic infants, the rate rose from 5.6 to 7.3; among Hispanic infants, it rose from 6.1 to 6.9; among Asians/Pacific Islanders, it rose from 6.5 to 8.0; and among American Indians/Alaska Natives, it rose from 6.1 to 7.4.
The percentage of infants with low birthweight varies widely among Hispanic subgroups. Data for 2004 indicate that among Hispanic women, those of Mexican origin had the lowest percentage low-birthweight infants (6.4 percent) and Puerto Ricans had the highest percentage (9.8 percent).
The percentage of infants born with very low birthweight (less than 1,500 grams, or 3 lb. 4 oz.) has increased gradually in recent years. In 2005, 1.49 percent of infants were very low birthweight, up from 1.48 percent in 2004, 1.42–1.46 percent from 1997 to 2003, 1.28–1.37 percent from 1989 to 1996, and 1.16–1.24 percent in each year from 1981 to 1988.
One reason for the recent increase in low birthweight is that the number of twin, triplet, and higher-order multiple births has increased. ^{6, 10, 112, 113} Multiple births are much more likely than singletons to be of low birthweight: 57 percent of twins and 94 percent of triplets, compared with 6 percent of singletons, were of low birthweight in 2004. However, even among singletons, low birthweight has increased. ⁶
Changes in the obstetric management of pregnancy with increases in induction and cesarean delivery, and an increase in the use of assisted reproductive technologies (ART) may also have played a role in the increase in low birthweight.¹¹⁴

table icon HEALTH1 HTML Table

excel icon HEALTH1 Excel Table

⁶ Martin, J.A., Hamilton, B.E., Sutton, P.D., Ventura, S.J., Menacker, F.J. and Kirmeyer, S. (2006). Births: Final data for 2004. National Vital Statistics Reports, 55(1). Hyattsville, MD: National Center for Health Statistics.

¹⁰ Hamilton, B.E., Martin, J.A., and Ventura, S.J. (2006). Births: Preliminary data for 2005. National Vital Statistics Reports, 55(11). Hyattsville, MD: National Center for Health Statistics.

²⁹ Kiely, J.L., Brett, K.M., Yu, S., and Rowley, D.L. (1994). Low birthweight and intrauterine growth retardation. In Wilcox, L.S., and Marks, J.S., (Eds.), From data to action: CDC's public health surveillance for women, infants, and children (pp. 185–202). Atlanta, GA: Centers for Disease Control and Prevention.

¹¹² Matthews, T.J., and MacDorman, M.F. (2006). Infant mortality statistics from the 2003 period linked birth/infant death data set. National Vital Statistics Reports, 54(16). Hyattsville, MD: National Center for Health Statistics.

¹¹³ Hack, M., Klein, N.K., and Taylor, H.G. (1995). Long-term developmental outcomes of low birthweight infants. The Future of Children: Low Birthweight, 5(1), 19–34. Los Altos, CA: Center for the Future of Children, the David and Lucile Packard Foundation.

¹¹⁴ MacDorman, M.F., Martin, J.A., Mathews, T.J., Hoyert, D.L., and Ventura, S.J. (2005). Explaining the 2001–02 Infant Mortality Increase: Data from the Linked Birth/Infant Death Data Set. National Vital Statistics Reports, 53(12). Hyattsville, Maryland: National Center for Health Statistics.