Donatelle 2000b.

Methods	Study design: RCT, dates not stated Country: USA Setting: 8 Oregon Women, Infants, and Children (WIC) programme counties SOS (Significant Other Supporter) Programme III
Participants	Probably similar to Donatelle 2000a; 186 pregnant smokers, randomised to E1 (N = 67); E2 (N = 59); Controls (N = 60)
Interventions	All participants received a 5As intervention (Ask, Advise, Assess, Assist, Arrange) E1 group: USD 25 voucher (local department store) for each month achieving validated abstinence E2 group: USD 25 voucher (local department store) for achieved abstinence + immediate feedback on risks to the foetus associated with CO results. CO ≤ 5 ppm confirmed monthly abstinence
Outcomes	Abstinence at end of pregnancy Biochemical validation by salivary cotinine < 30 ng/ml. CO < 5 ppm monthly
Notes	New for 2015 update Minimal information; emails to the author elicited no responses Funding not stated
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
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Abstinence biochemically validated
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	No information