1. NHS NHS Maternity Statistics, England 2010-11, December 1 2011, Maternity data reports, 2010-11 www.ic.nhs.uk/pubs/maternity1011
2. NHS Welsh Government. Maternity Statistics: Method of Delivery 2001-2011
3. ONS Office of National Statistics www.ons.gov.uk/ons/rel/vsob1/birth-summary-tables-england-and-wales/2013/stb-births-in-englandand-wales-2013.html
4. Global perspectives on elective induction of labor;Vogel;Clin Obstet Gynecol,2014