1. Blencowe, H., Cousens, S., Oestergaard, M., Chou, D., Moller, A. B., Narwal, R., et al. (2012). National, regional and worldwide estimates of preterm birth in the year 2010 with time trends since 1990 for selected countries: A systematic analysis and implications. The Lancet, 379(9832), 2162–2170.
2. Low Birth Weight (LBW) by Rural/Urban Residence. (2009). Centers for Disease Control and Prevention, National Center for Health Statistics, National Vital Statistics System. http://mchb.hrsa.gov/chusa12/rud/downloads/pdf/lbwpb.pdf
3. Institute of Medicine. (2007). Preterm birth: Causes, consequences, and prevention. Washington, DC: National Academies Press.
4. Muglia, L. J., & Katz, M. (2010). The enigma of spontaneous preterm birth. New England Journal of Medicine, 362(6), 529–535.
5. Behrman, R. E., & Butler, A. S. (Eds.). (2006). Preterm birth: Causes, consequences, and prevention. Washington, DC: National Academies Press.