4. Intensity of intervention meta‐regression analysis ‐ frequency of contact in intervention.

Group	Mean ES	‐95% CI	+95% CI	P	N
1	1.89	1.24	2.89	.03	8
2	1.11	0.86	1.43	.41	15
3	1.73	0.21	22.48	.003	8
4	1.23	1.01	1.51	.04	18
5	1.36	1.00	1.84	.05	10
6	1.38	1.19	1.60	.00	37

1 = Single contact during/at time of routine pregnancy care visits (but not ‘usual care’) without strategies to quit; 2 = Single contact, outside of ‘routine’ pregnancy care with strategies to quit; 3 = 2‐5 contacts to sustain motivation to stop smoking provided during/at time of routine pregnancy care visits; 4 = 2‐5 contacts to sustain motivation to stop smoking provided outside of routine care; 5 = > 5 contacts to sustain motivation to stop smoking provided during/at time of routine care visits; 6 = > 5 contacts to sustain motivation to stop smoking provided outside of routine care. 1 study, Campbell 2006, was treated as missing from this analysis as the intervention frequency was unclear.