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Preterm Birth

Narrative

Babies born preterm, before 37 completed weeks of gestation, are at increased risk of immediate and long-term complications, as well as death. Complications that can occur during the newborn period include respiratory distress, jaundice, anemia, and infection, while long-term complications can include learning and behavioral problems, cerebral palsy, lung problems, and vision and hearing loss. As a result of these risks, preterm birth is a leading cause of infant death and childhood disability. Although the risk of complications is greatest among those babies who are born the earliest, even those babies born “late preterm” (34 to 36 weeks of gestation) are more likely than full-term babies to experience morbidity and mortality.1

In 2010, 11.99 percent of infants were born preterm. Overall, 8.49 percent of babies were born at 34 to 36 weeks' gestation, 1.53 percent were born at 32-33 weeks, and 1.96 percent were "very preterm" (less than 32 weeks). Between 1990 and 2006, the preterm birth rate increased more than 20 percent, from 10.61 to 12.80 percent, but has declined in the four years since 2006 (data not shown in graph images or in data tables on this site). The greatest trends in preterm birth have been observed among the largest category of late preterm infants born at 34 to 36 weeks' gestation. For example, late preterm birth decreased by 7.1 percent from 2006 to 2010 (9.14 to 8.49 percent) while very preterm birth decreased by only 3.4 percent during the same time period (2.04 to 1.96 percent).

The preterm birth rate varies by race and ethnicity. In 2010, 17.12 percent of babies born to non-Hispanic Black women were born preterm, compared to 10.69 percent of babies born to Asian/Pacific Islander women. Among babies born to non-Hispanic White women, 10.77 percent were born preterm, while the same was true of 11.79 percent of babies born to Hispanic women and 13.60 percent of babies born to American Indian/Alaska Native women. The causes of preterm birth are not well understood but are linked to infection and vascular disease, as well as medical conditions, such as diabetes and hypertension, which may necessitate labor induction or cesarean delivery.2

1 Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Division of Reproductive Health. Prematurity. November 2009. Accessed: March 2, 2011

2 Goldenberg RL, Culhane JF, Iams JD, Romero R. Epidemiology and causes of preterm birth. Lancet. 2008 Jan 5;371(9606):75-84

Graphs

This image is described in the Data section.

infant preterm by gestation weeks graph

This image is described in the Data section.

preterm infants by maternal race graph

Data

Preterm Birth, by Completed Weeks of Gestation, 1990-2010
Year Percent of Live Births
Less than 32 weeks 32-33 Weeks 34-36 Weeks Total
Source: Martin, JA, Hamilton BE, Ventura SJ, Osterman, MK, Wilson, EC, Mathews, TJ. Births: Final data for 2010. National vital statistics reports; vol 61 no 1. Hyattsville, MD: National Center for Health Statistics. 2012.
Centers for Disease Control and Prevention. National Center for Health Statistics. VitalStats.  Accessed on 07/02/12.
1990 1.92 1.4 7.3 10.61
1995 1.89 1.42 7.68 10.99
2000 1.93 1.49 8.22 11.64
2005 2.03 1.6 9.09 12.73
2010 1.96 1.53 8.49 11.99

Preterm Birth Among Infants, by Maternal Race/Ethnicity,* 2010

Percent of Live births:

  • Non-Hispanic White 10.77
  • Non-Hispanic Black 17.12
  • Hispanic 11.79
  • American Indian/Alaska Native* 13.6
  • Asian/Pacific Islander*† 10.69

*Includes Hispanics.
†Separate data for Asians and Native Hawaiians and Other Pacific Islanders not available.

Source: Martin, JA, Hamilton BE, Ventura SJ, Osterman, MK, Wilson, EC, Mathews, TJ. Births: Final data for 2010. National vital statistics reports; vol 61 no 1. Hyattsville, MD: National Center for Health Statistics. 2012.