1. Defining early adolescent childbearing;Phipps;Am. J. Public Health,2002
2. Births: final data for 2002;Martin;Natl. Vital Stat. Rep.,2003
3. Teenage births in the United States: state trends, 1991–2000, an update;Ventura;Natl. Vital Stat. Rep.,2002
4. Smoot M. Delayed childbearing: increased maternal age at first birth and its association with labor and delivery outcomes [online]. 1997 [cited 2004 March 5]. Available from: URL: http://www.tdh.state.tx.us/bvs/reports/sreport2.pdf.
5. Center for Disease Control. Fact Sheet: pregnancy related mortality surveillance—United States 1991–1999 [online]. 2003 [cited 2004 July 6]. Available from: URL: http://www.cdc.gov/od/oc/media/pressrel/fs030220.htm.