Methods	Cluster-randomised controlled trial to test the effectiveness of the ALA smoking in pregnancy intervention to support women to stop smoking in pregnancy Study conducted in 11 private obstetric practices in Michigan and Upper Wisconsin (USA), with recruitment from August 1985 to June 1986
Participants	Inclusion criteria: 24 physicians in 11 private practices participated in the study (12 family physicians and 12 obstetricians). Study practices randomised into ‘roughly equal groups’. Women smoking at first antenatal appointment, less than 28 weeks’ gestation were recruited to study Exclusion criteria: Not further specified. Recruitment: All women attending those clinics invited to participate. After giving informed consent, each woman was assigned a code number and had a questionnaire pack placed in her chart. 639 women screened (5 refusals), 206 smokers (32%), 69/209 had quit since becoming pregnant and 137 continuing smokers were included in the study (C = 70, I = 67) Baseline characteristics: Pre-pregnancy mean cigs per day = 20; current mean cigarettes per day = 11 98% white, 70% married, majority (80%) completed high school Progress+ coding: None.
Interventions	Control: 3 counselling sessions with physician on risks, ashtrays removed from waiting rooms and staff asked not to smoke in front of patients Intervention: Control plus (i) use of ALA materials (because you love your baby flip chart; because you love your baby packets, because you love your baby poster) (ii) encouragement to send off for materials (freedom from smoking manual), (iii) slide tape presentation at each women’s first obstetrics visit Main intervention strategy: Counselling (multiple intervention) compared to less intensive intervention Intensity: Frequency (C = 3, I = 5), Duration (C = 1, I = 2). Intervention provided by existing staff (physicians): Effectiveness study
Outcomes	Self-reported smoking abstinence at 32-36 weeks’ gestation (late pregnancy*) and first postpartum visit (timing not specified but assumed is standard 6 weeks pp visit), 0-5 months pp*
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Stratified by size - and then assigned by coin toss.
Allocation concealment (selection bias)	High risk	Allocation not concealed with coin toss randomisation.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition: 7 miscarriages (C = 4, I = 3), 2 therapeutic abortions (C = 0, I = 2), 11 moved (C = 6, I = 5) and 8 had an incomplete dataset (C = 4, I = 4). Those with incomplete dataset were re-included as continuing smokers in this review (C = 60, I = 57)
Selective reporting (reporting bias)	Low risk	Primary outcomes appear to be reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	High risk	No biochemical validation of smoking status (self-report only)
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind providers and women to educational intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	Low risk	Exact rates not reported - but ‘only minor deviations’ suggests very high implementation
Equal baseline characteristics in study arms	Unclear risk	Not reported.
Contamination of control group	Low risk	Cluster-randomised by clinic - so unlikely to have ALA materials