| ||Maternal age is a risk factor for preterm birth, with higher preterm birth rates found among the youngest and oldest mothers in the U.S. |
| ||During 2008-2010 (average) in the United States, late preterm birth rates were highest for women ages 40 and older (11.8%), followed by women under age 20 (9.3%), ages 30-39 (8.8%) and ages 20-29 (8.2%). |
| ||Of all infants born during 2008-2010 (average), 9.9% were to mothers under the age of 20, 52.6% were to mothers ages 20-29 years, 34.8% were to mothers ages 30-39 years, and 2.8% were to mothers ages 40 and older. |
National Center for Health Statistics, final natality data.
Retrieved May 22, 2013, from www.marchofdimes.com/peristats.