Methods	Randomised controlled trial of motivational enhancement therapy to support women to stop smoking in pregnancy Dates of research and location not stated. Assume USA from author affiliations
Participants	Inclusion criteria: Opioid-dependent women, <= 26 weeks’ gestation, receiving methadone, currently smoking at least 5 cigarettes per day, enrolled in hospital prenatal program. Exclusion criteria: Not further specified. Recruitment: During first 48 hours of 7-day residential program. 77 women randomised. 14 women excluded from analysis due to miscarriage, abortion, premature delivery and miscalculated gestational age. 63 included in analysis (I = 30, C = 33) Baseline characteristics: Mean cigarettes per day 19.9 (SD 11.5). Approximately 50% had lifetime major depressive disorder, 32% were depressed in last month, and 39% had anxiety disorder. 84% African American, 79% single, 97% unemployed. 94% had less than high school education. Not coded for equity analysis as outcomes not able to be included in this review
Interventions	Control: Health practitioner advice by trained research staff and printed materials from American Lung Association and American Cancer Society Intervention: As control + Motivational Enhancement therapy using ‘Project MATCH’ manual with modifications for nicotine dependence, provided over 4 sessions by masters level research associates Main strategy and intensity not coded as outcomes unable to be included in meta-analysis
Outcomes	Mean cigarettes per day, mean exhaled CO, mean cotinine, movement in stages of change were collected and authors report that there was no significant difference. However, not actual figures were provided to be able to include these outcomes in meta-analysis in this review
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Just states participants were ‘randomly assigned’ to 1 of 2 conditions
Allocation concealment (selection bias)	Unclear risk	Not stated
Incomplete outcome data (attrition bias) All outcomes	High risk	Participant attrition was 14% (n = 9). Final figures not reported so unclear how many included in analysis
Selective reporting (reporting bias)	Unclear risk	Actual smoking rates not reported, despite this being a primary outcome for the study. However, authors did not claim results were significant
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Unclear risk	Cotinine and CO validation measured, but not reported.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Intervention providers and women not blinded as counselling intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not stated.
Incomplete implementation	Unclear risk	Process evaluation not reported.
Equal baseline characteristics in study arms	Unclear risk	Intervention group had lower mean education levels, were more likely to be Caucasian, and had higher rates of pre-pregnancy cigarettes per day. Other factors equal
Contamination of control group	Low risk	Masters level research associates provided the intervention.