Lowe 1997

Methods	Setting: prenatal clinic, USA Recruitment: volunteer recent quitters
Participants	78 pregnant women who had quit within previous 3 months (9 exclusions and 19 lost to follow‐up not included) Age/smoking history not described Therapists: health educator. Reinforcement provided by doctors and nurse trained at workshops
Interventions	1. 10 minutes counselling with health educator. Relapse prevention materials at 5th grade reading level, enhanced social support with materials, chosen 'buddy'. Reinforcement at routine visits by clinic staff 2. Usual care, including nurse advice
Outcomes	Continued abstinence at end of pregnancy (exact period not specified) Validation: saliva thiocyanate
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomisation method not described
Allocation concealment (selection bias)	Unclear risk	No details given
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Blinding not relevant because of nature of the intervention (all relevant personnel involved in delivering intervention); any potential causes of performance bias could be considered deliberate elements of the intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Biochemical validation used
Incomplete outcome data (attrition bias) All outcomes	Low risk	Greater loss to follow‐up in control, so losses to follow‐up not included in denominators to give conservative relapse prevention
Other bias	Unclear risk	Potential contamination, "the issue of contamination, while monitored, is one that remains a concern"