Table 1: Published and simulated number of events, patients and event rates, by indicator and CCG. Data from the National Child and Maternal Health Intelligence Network [25] and NHS Digital [26].

*Scenario 1 (no new events) = published events/(deliveries + extra deliveries) where extra deliveries= published deliveries/(1-opt out rate)-published deliveries; scenario 2 (average events) = ((extra deliveries*event rate)+published events)/(deliveries + extra deliveries); scenario 3 (max. events) = (events+ extra deliveries)/(deliveries + extra deliveries).

	Caesarean section			Very low birth weight
	Bradford City CCG	Merton CCG	Oldham CCG	Bradford City CCG	Merton CCG	Oldham CCG
CCG opt out rate (%) [26]	0.3	2.74	10.08	0.3	2.74	10.08
Published maternity data [25]
Events	478	948	792	36	39	39
Deliveries	2024	3265	2797	1657	3219	3195
Event rate	23.6	29	28.3	2.17	1.21	1.22
(95% CI)	(21.8,25.5)	(27.5,30.6)	(26.7,30.0)	(1.57,2.99)	(0.89,1.65)	(0.89,1.66)
New event rate (95% CI)*
Scenario (1)	23.5	28.2	25.5	2.17	1.18	1.1
	(21.8,25.4)	(26.7,30.0)	(24.0,27.0)	(1.57,2.99)	(0.86,1.61)	(0.80,1.50)
Scenario (2)	23.6	29	28.3	2.17	1.21	1.2
	(21.8,25.5)	(27.5,30.6)	(26.8,30.0)	(1.57,2.99)	(0.89,1.64)	(0.90,1.63)
Scenario (3)	23.8	31	35.6	2.47	3.93	11.2
	(22.0,25.7)	(29.4,32.6)	(34.0,37.3)	(1.82,3.33)	(3.32,4.64)	(10.2,12.3)