1. Hospital episode statistics: NHS maternity statistics. England 2012-132013.
2. National vital statistics reports. Births: final data for 2012;Martin,2013
3. Caesarean section: NICE clinical guideline CG132;NICE,2011
4. Classification of urgency of caesarean section – a continuum of risk;Royal College of Obstetricians and Gynaecologists RCoA,2010
5. Assessment of a modified four-category classification of urgency of caesarean section;Kinsella;J Obstet Gynaecol,2009