Comparison 1. Smoking cessation interventions: counselling vs usual care.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Abstinence in late pregnancy	30	12432	Risk Ratio (M‐H, Random, 95% CI)	1.44 [1.19, 1.73]
1.1 Single interventions	13	4565	Risk Ratio (M‐H, Random, 95% CI)	1.33 [1.01, 1.74]
1.2 Multiple interventions	11	4048	Risk Ratio (M‐H, Random, 95% CI)	1.42 [1.04, 1.93]
1.3 Tailored interventions	6	3819	Risk Ratio (M‐H, Random, 95% CI)	1.49 [1.01, 2.20]
2 Abstinence in late pregnancy: biochemically validated only	21	9703	Risk Ratio (M‐H, Random, 95% CI)	1.23 [1.04, 1.45]
2.1 Single interventions	9	3903	Risk Ratio (M‐H, Random, 95% CI)	1.12 [0.90, 1.41]
2.2 Multiple interventions	8	3823	Risk Ratio (M‐H, Random, 95% CI)	1.26 [0.92, 1.73]
2.3 Tailored interventions	4	1977	Risk Ratio (M‐H, Random, 95% CI)	1.42 [0.84, 2.41]
3 Continued abstinence (relapse prevention) in late pregnancy for spontaneous quitters	8	688	Risk Ratio (M‐H, Random, 95% CI)	1.06 [0.93, 1.21]
3.1 Single interventions	2	100	Risk Ratio (M‐H, Random, 95% CI)	1.00 [0.93, 1.07]
3.2 Multiple interventions	3	297	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.93, 1.26]
3.3 Tailored interventions	3	291	Risk Ratio (M‐H, Random, 95% CI)	1.19 [0.97, 1.46]
4 Abstinence at 0 to 5 months postpartum	11	2926	Risk Ratio (M‐H, Random, 95% CI)	1.59 [1.26, 2.01]
4.1 Single interventions	7	1924	Risk Ratio (M‐H, Random, 95% CI)	1.58 [1.21, 2.06]
4.2 Multiple interventions	3	635	Risk Ratio (M‐H, Random, 95% CI)	2.55 [1.17, 5.53]
4.3 Tailored interventions	1	367	Risk Ratio (M‐H, Random, 95% CI)	1.18 [0.62, 2.25]
5 Abstinence at 6 to 11 months postpartum	6	2458	Risk Ratio (M‐H, Random, 95% CI)	1.33 [1.00, 1.77]
5.1 Single interventions	3	1098	Risk Ratio (M‐H, Random, 95% CI)	1.36 [0.99, 1.86]
5.2 Multiple interventions	2	733	Risk Ratio (M‐H, Random, 95% CI)	1.69 [0.48, 5.96]
5.3 Tailored interventions	1	627	Risk Ratio (M‐H, Random, 95% CI)	0.99 [0.40, 2.46]
6 Abstinence at 12 to 17 months postpartum	2	431	Risk Ratio (M‐H, Random, 95% CI)	2.20 [1.23, 3.96]
6.1 Single interventions	2	431	Risk Ratio (M‐H, Random, 95% CI)	2.20 [1.23, 3.96]
7 Abstinence at 18+ months postpartum	3	798	Risk Ratio (M‐H, Random, 95% CI)	0.98 [0.50, 1.92]
7.1 Single interventions	1	239	Risk Ratio (M‐H, Random, 95% CI)	1.17 [0.31, 4.42]
7.2 Multiple interventions	2	559	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.43, 2.00]
8 Reduction in late pregnancy: biochemically validated	2	1002	Risk Ratio (M‐H, Random, 95% CI)	0.79 [0.49, 1.28]
8.1 Single interventions	1	756	Risk Ratio (M‐H, Random, 95% CI)	0.63 [0.34, 1.20]
8.2 Multiple interventions	1	246	Risk Ratio (M‐H, Random, 95% CI)	1.04 [0.51, 2.13]
9 Reduction in late pregnancy: self reported (various definitions)	5	839	Risk Ratio (M‐H, Random, 95% CI)	1.66 [1.27, 2.17]
9.1 Single interventions	2	323	Risk Ratio (M‐H, Random, 95% CI)	1.61 [1.06, 2.43]
9.2 Multiple interventions	3	516	Risk Ratio (M‐H, Random, 95% CI)	1.74 [1.17, 2.57]
10 Biochemical measures in late pregnancy: mean cotinine	6	1884	Std. Mean Difference (IV, Random, 95% CI)	‐0.44 [‐0.76, ‐0.12]
10.1 Single interventions	4	1443	Std. Mean Difference (IV, Random, 95% CI)	‐0.35 [‐0.69, ‐0.02]
10.2 Multiple interventions	2	441	Std. Mean Difference (IV, Random, 95% CI)	‐1.20 [‐3.64, 1.24]
11 Mean cigarettes per day in late pregnancy	11		Std. Mean Difference (IV, Random, 95% CI)	Totals not selected
11.1 Single interventions	7		Std. Mean Difference (IV, Random, 95% CI)	0.0 [0.0, 0.0]
11.2 Multiple interventions	2		Std. Mean Difference (IV, Random, 95% CI)	0.0 [0.0, 0.0]
11.3 Tailored interventions	2		Std. Mean Difference (IV, Random, 95% CI)	0.0 [0.0, 0.0]
12 NICU admissions	2	1140	Risk Ratio (M‐H, Random, 95% CI)	0.82 [0.52, 1.29]
12.1 Single interventions	1	762	Risk Ratio (M‐H, Random, 95% CI)	0.71 [0.47, 1.07]
12.2 Tailored interventions	1	378	Risk Ratio (M‐H, Random, 95% CI)	1.17 [0.55, 2.46]
13 Very low birthweight infants (< 1500 g)	2	1666	Risk Ratio (M‐H, Random, 95% CI)	1.27 [0.60, 2.71]
13.1 Single interventions	1	731	Risk Ratio (M‐H, Random, 95% CI)	0.91 [0.32, 2.59]
13.2 Tailored interventions	1	935	Risk Ratio (M‐H, Random, 95% CI)	1.83 [0.62, 5.43]
14 Preterm births	5	2653	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.64, 1.27]
14.1 Single interventions	3	1571	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.60, 1.17]
14.2 Tailored interventions	2	1082	Risk Ratio (M‐H, Random, 95% CI)	1.13 [0.46, 2.80]
15 Mean birthweight	11	4925	Mean Difference (IV, Random, 95% CI)	40.27 [7.87, 72.66]
15.1 Single interventions	6	1995	Mean Difference (IV, Random, 95% CI)	52.87 [‐0.41, 106.15]
15.2 Multiple interventions	2	588	Mean Difference (IV, Random, 95% CI)	72.91 [‐89.12, 234.95]
15.3 Tailored interventions	3	2342	Mean Difference (IV, Random, 95% CI)	23.25 [‐52.12, 98.62]
16 Perinatal deaths	2		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
16.1 Single interventions	1	130	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
16.2 Tailored interventions	1	935	Risk Ratio (M‐H, Random, 95% CI)	1.10 [0.52, 2.31]
17 Stillbirths	4	2212	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.51, 2.30]
17.1 Single interventions	2	859	Risk Ratio (M‐H, Random, 95% CI)	2.58 [0.38, 17.48]
17.2 Tailored interventions	2	1353	Risk Ratio (M‐H, Random, 95% CI)	0.92 [0.41, 2.10]
18 Neonatal deaths	3	2095	Risk Ratio (M‐H, Random, 95% CI)	2.06 [0.61, 6.92]
18.1 Single interventions	1	762	Risk Ratio (M‐H, Random, 95% CI)	1.17 [0.07, 18.65]
18.2 Tailored interventions	2	1333	Risk Ratio (M‐H, Random, 95% CI)	2.35 [0.61, 9.07]
19 Low birthweight infants (< 2500 g)	6	3836	Risk Ratio (M‐H, Random, 95% CI)	0.87 [0.70, 1.08]
19.1 Single interventions	2	1460	Risk Ratio (M‐H, Random, 95% CI)	0.79 [0.56, 1.11]
19.2 Multiple interventions	1	414	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.45, 2.61]
19.3 Tailored interventions	3	1962	Risk Ratio (M‐H, Random, 95% CI)	0.93 [0.66, 1.32]