U.S. Department of Health and Human Services, Health Resources and Services Administration

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Low Birth Weight

Low birth weight is a leading cause of neonatal mortality (death before 28 days of age). Low birth weight infants are more likely to experience long-term disability or die during the first year of life than are infants of normal weight.

According to preliminary data, 8.2 percent of infants were born low birth weight (less than 2,500 grams or 5 pounds 8 ounces) in 2008; this rate was unchanged from the previous year. In 2006, the rate of low birth weight was the highest recorded in four decades (8.3 percent). The increase in multiple births, which are at high risk of low birth weight, strongly influenced this increase; however, rates of low birth weight also rose for singleton births.

In 2008, the rate of low birth weight was much higher among infants born to non-Hispanic Black women (13.7 percent) than infants born to mothers of other racial/ethnic groups. The second highest rate, which occurred among Asian/Pacific Islanders, was 8.2 percent, followed by a rate of 7.4 percent among American Indian/Alaska Natives. Low birth weight occurred among 7.2 percent of infants born to non-Hispanic White women, while infants of Hispanic women experienced the lowest rate (7.0 percent). The low birth weight rate remained unchanged over the previous year for infants born to non-Hispanic White mothers, while the rate declined for infants born to non-Hispanic Black and American Indian/Alaska Native mothers and increased for infants born to Hispanic and Asian/Pacific Islander mothers.

Low birth weight also varied by maternal age. In 2007 (the latest year for which data are available), the rate of low birth weight was highest among babies born to women younger than 15 years of age (12.4 percent), followed by babies born to women aged 40–54 years (11.5 percent). The lowest rates occurred among babies born to mothers aged 25–29 years and 30–34 years (7.4 and 7.6 percent, respectively; data not shown).

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