Table 1.

Cohorts included in the analysis

Cohort	Date of birth range	Included child health reviews		Date of CHSP-PS extract used in analysis
		Review name	Upper age limit by which the review should be completed
Old child health programme	1 November 1998–31 October 1999	10 day	None specified	November 2003
		6–8 week	12 weeks
		8–9 month	10 months
		22–24 month	26 months
		39–42 month	44 months
New child health programme	1 July 2007–30 June 2008	10 day	28 days	February 2009
		6–8 week	12 weeks

CHSP-PS, Child Health Surveillance Programme—PreSchool.