1. World Health Organization, Preterm birth, Fact sheet No363, [internet]; 2012 November. Available from: http://www.who.int/mediacentre/factssheets/fs363/en/ [retrieved 8/22/13].
2. Martin JA, Hamilton BE, Ventura SJ, Osterman MJK, Matthews TJ, Births: Final data for 2011. National Vital Statistics Reports, 62(1) US Department of Health and Human Services Jun. 28; 2013.
3. Surgeon General’s Conference Outlines Agenda to Prevent Preterm Birth [internet], 2008 June 19. Available from: [retrieved 8/23/13].
4. Preventing preterm birth: analysis of trends and potential reductions with interventions in 39 countries with very high human development index;Chang;Lancet,2013
5. Preterm birth: causes, consequences, and prevention,2007