1. DeFrances CJ, Hall MJ, Podgornik MN: 2003 National Hospital Discharge Survey. Advance Data from Vital and Health Statistics, no. 359. Hyattsville, MD, National Center for Health Statistics, 2005
2. Martin JA, Hamilton BE, Sutton PD, et al: Births: Final Data for 2003. National Vital Statistics Reports; vol. 54, no. 2. Hyattsville, MD, National Center for Health Statistics, 2005
3. Hamilton BE, Martin JA, Ventura SJ, et al: Births: Preliminary Data for 2004. National Vital Statistics Reports; vol. 54, no. 6. Hyattsville, MD, National Center for Health Statistics, 2005
4. Organization for Economic Cooperation and Development. OECD Health Data 2005: Statistics and Indicators for 30 Countries. Frequently Requested Data, 2005
5. Office for National Statistics. Birth Statistics. Review of the Registrar General on births and patterns of family building in England and Wales, 2004. Series FM 1 no. 33. London, Office for National Statistics, 2005. Available at: http://www.statistics.gov.uk