Epidemiology of Preterm Births in the United States

Document Type


Publication Date



Preterm delivery is one of the important causes of infant morbidity and mortality in the United States (U.S.). Annually, 12% of infants are born preterm in the U.S. and preterm birth related causes of death account for approximately 35% of all infant deaths. Using the latest (2012) National Survey of Children’s Health, the study aims to estimate the prevalence rates of preterm birth in the U.S., and identify key risk factors associated with it. Data (n=42,282) was obtained from the 2012 NSCH. Using the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists recommendations, preterm birth was defined as one occurring less than 37 completed weeks of gestation from the first day of Page 26 2015 Appalachian Student Research Forum the last menstrual period. Based on existing literature, the following maternal and child characteristics were included as potential factors associated with preterm birth in the U.S. – infant gender, race, maternal smoking or maternal exposure to secondhand smoke (SHS), family income and maternal general health status. Descriptive statistics were reported using frequencies and proportions. Multiple logistic regression analyses were conducted to assess the association of selected variables with the preterm birth. Overall, 10.65% of live births were born preterm in the U.S. during 2012. Preterm birth prevalence rates were higher among males (12.07%), non-Hispanic blacks (14.34%) and those born to mothers who were smokers or exposed to secondhand smoke during pregnancy (23.8%). Males had higher odds of being born preterm (OR 1.07 95% CI 1.01-1.15) than females. Non-Hispanic White is less likely to be born preterm (OR 0.86 95% CI 0.74-0.99) compared to non-Hispanic black. Infants born to mothers who were smokers or exposed to SHS during pregnancy had higher odds of being born preterm (OR 1.05, 95% CI 0.97-1.13) compared to those born to women who were non-smokers and not exposed to SHS. Infants born to women who reported better general health status were less likely to be born preterm (Excellent/Very good vs Fair/Poor: OR 0.51 95% CI 0.46-0.56, Good vs Fair/Poor: OR 0.68 95% CI 0.61-0.75) than referent group. Approximately one-tenths of live births in the U.S. were born preterm. Study findings demonstrated infant race, gender, maternal general health status and maternal smoking or secondhand smoke exposure during pregnancy as factors associated with preterm birth. Determining these factors is important in the development of effective intervention programs and policies to reduce the rates of preterm birth in the U.S.


Johnson City, TN

This document is currently not available here.