Study	Reason for exclusion
Albrecht 2011	Program description only, not a randomised controlled study.
Andrews 2007	Women included were not‐pregnant, plus quasi‐randomised study design.
Boshier 2003	Cohort study, not a randomised study design.
Bowden 2010	Cohort study only, no control or comparison group.
Brandon 2012	Part of the intervention is provided during pregnancy but primary aim of the study is to prevent relapse after pregnancy and postpartum outcomes only reported.
Britton 2006	Quasi‐experimental design. Control and experimental convenience samples collected consecutively.
Britton 2013	Retrospective audit only.
Chan 2005	Controlled observational study of bupropion for smoking cessation in pregnancy.
Chi 2015	Directed at partners of smoking women not pregnant women who smoke.
Coleman 2007	Randomised controlled trial of pharmacological intervention with equal psychosocial support in both arms.
Culp 2007	Controlled trial/evaluation of "The Community‐Based Family Resource and Support" (CBFRS) Program. Control group not randomised.
DeVries 2006	Quasi‐cluster‐randomised study with inadequate sequence generation (40 practices selected with matched controls).
Disantis 2010	Non‐randomised postpartum intervention to promote smoking cessation and breastfeeding.
Dixon 2009	Longitudinal cohort study only.
Edwards 2009	Evaluation of 'SMART moms' project, which has no control group.
El‐Mohandes 2013	Randomised‐controlled trial of pharmacological interventions (nicotine replacement therapy) with equal psychosocial support in both study arms.
Emmons 2000	Controlled trial/evaluation of the "Healthy Baby Second Hand Smoke Study" uses historical controls. Good documentation of implementation problems.
Ershoff 1983	The intervention took place in 1 HMO clinic with historical controls from the same clinic and concurrent controls from a second clinic. There was no randomisation of clinics and no adjustment of the data for clustering.
Everett‐Murphy 2010	Evaluation of smoking cessation counselling using a historical control group only (pre‐post study design, not randomised and no contemporary control group).
Ferguson 2012	Pregnant women excluded from this study (non‐pregnant study population).
Ferreira‐Borges 2005	Pre‐test post‐test control group design (not randomised).
Fish 2011	Intervention aimed at partners of pregnant women only. Pregnant women not included in the intervention.
French 2007	Controlled clinical trial of postpartum relapse prevention. Excluded as not a trial during pregnancy, and not randomised.
Gadomski 2011	Evaluation of 'The BABY and ME‐Tobacco Free' program for relapse prevention postpartum. Quasi‐experimental design with non‐randomised control group (matched randomly selected controls).
Gebauer 1998	Study of effect of one 15‐minute counselling session and a follow‐up telephone call, performed 1994‐95, using historical controls from 1993‐1994.
Gillies 1987	In this controlled clinical trial the intervention was carried out in 1 hospital with another hospital in the same city acting as a control, after a prior descriptive study which showed the similarity between the 2 in terms of social and demographic factors including smoking. There was no randomisation and recruitment differed substantially across the 2 sites. Data for smoking reduction and smoking cessation are combined in the paper with no separate data on cessation and no adjustment for clustering.
Grange 2005	Cohort study design.
Hahn 2005	Controlled trial with a volunteer sample of non‐pregnant contest registrants, compared with a randomly selected group of smokers not exposed to the campaign/contest. Context registrants not randomised and there is evidence of differences between groups.
Hannover 2008	Counselling intervention aimed at relapse prevention postpartum only. Screened for participation during birth admission.
Hayes 2013	Consecutive recruitment.
Herbert 2011	Intervention to reduce 'Environmental Tobacco Smoke' exposure aimed at postpartum relapse prevention only.
Higgins 2004	Pilot study with 37/53 participants consecutively assigned (not randomised).
Hotham 2006	Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) with equal psychosocial support in both study arms.
Huang 2013	Assignment by alternate odd/even dates.
Hymowitz 2006	Postpartum trial only which measures paediatrician implementation of smoking cessation and relapse prevention interventions.
Jaakola 2001	Controlled study, not randomised, of effects of a population‐based smoking cessation program and its impact on smoking in pregnancy. Controls were matched on inclusion criteria from another district.
Jimenez‐Muro 2013	Postpartum intervention.
Johnston 2011	Cohort smoking data from a randomised controlled trial of maternal vaccines.
Kaper 2006	Non‐pregnant population.
Kapur 2001	Randomised controlled trial of pharmacotherapy with equal psychosocial support in both study arms.
Karatay 2010	Evaluation of a motivational interviewing intervention with no control group.
Kazemi 2012	Intervention aimed at partners of pregnant women only to reduce passive tobacco smoke exposure for pregnant women in Iran.
Kientz 2005	Unable to determine number allocated to each trial arm and unclear what happened if unequal flip of coin.
Langford 1983	Prenatal classes, rather than individual women, were randomly allocated to provide the intervention or not. The intervention was provided in late pregnancy with no outcome data collected during pregnancy but only data 4 months after birth. There was no adjustment for cluster‐randomisation in the analysis of the study findings.
Lee 2008	Intervention aimed at partners of pregnant women only to reduce passive tobacco smoke exposure for pregnant women in China.
Levine 2013	Intervention is for postpartum women.
Loke 2005	Intervention aimed at smoking cessation in men (partners of pregnant women).
Lowe 1998a	Quasi‐randomised study with inadequate sequence generation (allocation by alternate clinic weeks).
Lowe 1998b	Quasi‐randomised study with inadequate sequence generation (allocation by alternate clinic weeks).
MacArthur 1987	Quasi‐randomised study with inadequate sequence generation (allocation by date of clinic visit).
Miller 2003	A pilot study of a pharmacological intervention (bupropion).
Mullen 1997	Study designed to promote postpartum smoking cessation (not antepartum or part of a trial conducted in pregnancy).
Murray 2008	Intervention to promote smoking cessation among a general (not specifically pregnant) primary care population.
NCT00507975	Double‐blind study of nicotine replacement therapy.
NCT00744913	Randomised controlled trial of pharmacotherapy with equal psychosocial support in both study arms.
O'Connor 1992	Quasi‐randomised study with inadequate sequence generation (alternate allocation according to day of week).
Oncken 2008	Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) with equal psychosocial support in both arms.
Peden 2008	Quasi‐randomised study with sequential allocation to study arms.
Phillips 2012	Intervention aimed at postpartum relapse prevention only. Mother's were recruited during infant's admission to NICU.
Polanska 2011	Observational cohort study only with no comparison group.
Pollak 2007	Randomised controlled trial of pharmacotherapy (nicotine replacement therapy) and equal psychosocial support in both arms.
Pollak 2014	Intervention aimed at partners of women who smoke.
Power 1989	The intervention in this trial was unusual in that the focus was on anticipated benefits of smoking cessation to women themselves (not on harm to the fetus and infant), and on alternative coping strategies, with a designated midwife‐facilitator to answer queries and provide friendly advice and encouragement. The intervention was carried out in 1 hospital with another being a comparison setting, after a prior study which showed the similarity between the 2 in social and demographic factors including smoking rates. There was no randomisation. Recruitment differed significantly across the 2 hospitals. Data for smoking cessation and smoking reduction are combined with no separate data on cessation and no adjustment for clustering.
Ratner 1999	Postpartum intervention only. No interventions in pregnancy.
Reitzel 2010	Intervention aimed at postpartum relapse prevention only.
Rush 1992	Quasi‐experimental study with inadequate sequence generation (group allocation by alternate weeks).
Scott 2000	This controlled clinical trial of the impact of using interactive software to promote smoking cessation, was excluded as it used historical controls.
Shakespeare 1990	Not a smoking in pregnancy intervention.
Simmons 2014	Not a randomised controlled trial.
Stanton 2004	Intervention aimed at partner's of pregnant women only. Aim was to maximise potential of life‐changing period for men too. Did not include pregnant women.
Suplee 2004	Randomised trial of relapse prevention counselling in the postpartum period only (not pregnancy).
Sutton 2007	Intervention of tailored smoking cessation letters, self‐help materials and counselling for the general population (not specifically pregnant women).
Valanis 2001	This prospective controlled clinical trial design to test the effect of a low intensity intervention, used historical controls.
Valbo 1991	Quasi‐experimental study with inadequate sequence generation (3 months consecutive recruitment for each arm).
Velasquez 2014	Preconceptual intervention and unable to determine how many participants were pregnant.
Wadland 2007	General study population (not pregnant). Implementation trial to change provider behaviour and increase referrals to quitline. Estimated smoking cessation outcome data only.
Wen 2016	Not pregnant women.
Wiggins 2004	Cluster‐randomised controlled trial comparing 2 postnatal interventions to improve maternal health.
Wilkinson 2010	Quasi‐experimental design with a non‐randomised controlled pre‐post test study design.
Windsor 2000a	Quasi‐experimental study with inadequate sequence generation (80% control group not randomly assigned).
Winickoff 2010	Intervention aimed at postpartum relapse prevention only with women recruited during birth admission.
Wisborg 1998	This randomised study of the effect of midwifery training on smoking cessation intervention implementation and pregnancy outcomes, was excluded due to concerns about allocation concealment (clinic day allocation).
Wisborg 2000	Randomised controlled trial of a pharmacological intervention (nicotine replacement therapy) and equal psychosocial support in both study arms.
Yilmaz 2006	Postnatal intervention in pediatric setting.

HMO: Health Maintenance Organisation
 NICU: neonatal intensive care unit