Table 3

Effect of intervention (after vs before) on probability of quitting by delivery

Variable	OR	95% CI	Pr(>\|z\|)
Intercept: baseline	0.13	0.09 to 0.19	<0.001
After implementation of intervention, compared with before
After intervention	1.81	1.55 to 2.12	<0.001
Ethnic group, compared with white
Caucasian	2.52	1.837 to 3.44	<0.001
SEP category (based on IMD score) compared with middle three-fifths of distribution
Least deprived fifth	2.75	2.386 to 3.18	<0.001
Most deprived fifth	0.4	0.42 to 0.65	<0.001
Maternal age category, compared with 21–30 years
15–20 years	0.75	0.655 to 0.87	<0.001
31–40 years	1.43	1.29 to 1.60	<0.001
41–55 years	1.14	0.76 to 1.71	0.526
Engagement with smoking cessation services, compared with not referred
Referred, quit date	4.18	3.53 to 4.94	<0.001
Referred, no quit date	3.33	2.99 to 3.71	<0.001
Time since start of intervention, compared with before
Each additional month	1.02	1.00 to 1.03	<0.050

9967 valid cases included in model (6.6% cases with missing data excluded).
SEP, socioeconomic position (categories defined by fifths of Index of Multiple Deprivation (IMD) score)