Low Birth Weight. Disorders related to short gestation and low birth weight are the second leading cause of neonatal mortality in the United States. In 2006, 123,230 babies born to residents of U.S. cities with populations over 100,000 were low birth weight (weighing less than 2,500 grams, or 5 pounds 8 ounces); this represents 8.8 percent of infants in U.S. cities. The 2006 percentage of urban infants born low birth weight was 6 percent higher than the percentage among all U.S. infants (8.3 percent), though this gap has decreased somewhat since 1990.
Very Low Birth Weight. Infants born very low birth weight (less than 1,500 grams, or 3 pounds 4 ounces) are at highest risk for poor health outcomes. In 2006, nearly 1.7 percent of live births in cities with populations over 100,000 were very low birth weight. This exceeded the rate of very low birth weight nationwide by 13 percent.