Methods	Randomised controlled trial evaluating provision of videotaped vignettes for promoting smoking cessation and relapse prevention during pregnancy Study conducted in a community-based university setting, Texas, USA. Data collection dates not reported
Participants	Inclusion criteria: Volunteers who were willing to quit within 2 weeks. Exclusion criteria: Women smoking < 3 cigarettes per day; < 18 years; > 30 weeks’ pregnant; do not have a working video recorder (approximately 12% Americans); depressed Recruitment: Through local media, such as newspaper, radio, subscriber letters, community business flyers, waiting room posters 146 women screened and 82 women who met inclusion criteria were randomised (C = 40, I = 42) Baseline characteristics: Mean cigarettes/day at first visit: C = 14.5, I = 17.3. Progress+ coding: None.
Interventions	Control: Received a quit calendar and tip guide. Intervention: As for control plus were mailed a video with 6 × 25-30 minute vignettes covering a range of topics and strategies from initial quitting to relapse prevention Main intervention strategy: Counselling (single intervention) compared to a less intensive intervention Intensity: Frequency (C = 2, I = 2), Duration (C = 1, I = 4). Intervention provided by study staff: efficacy study.
Outcomes	Biochemically validated point prevalence abstinence obtained within 2-3 days of quit date, 4-5 weeks after the quit date (late pregnancy)* and 1 month postpartum (0-5 months postpartum*). Participant evaluation of intervention materials. Associated references report association of quitting and depressive disorders. CES-D scores at baseline only
Notes	Authors say women in this study tend to be heavier smokers than described in previous studies
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not stated.
Allocation concealment (selection bias)	Unclear risk	Not stated.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Only 61% of participants completed all assessments. All those with missing data were treated as continuing smokers in this review
Selective reporting (reporting bias)	Low risk	Pre-specified outcomes reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Low risk	All reports of abstinence were validated by measurement of salivary cotinine
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Video mailed to participants. Not clear if UC givers were aware of group allocation
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	High risk	Process evaluation showed only 53% of the intervention group viewed 1-3 of the 6 videos. 47% did not view them
Equal baseline characteristics in study arms	Low risk	No significant difference in socioeconomic variables between groups
Contamination of control group	Low risk	Video mailed out to participants only.