Methods	4-armed cluster-randomised controlled trial of counselling interventions to support women to stop smoking in pregnancy Study conducted in primary health care clinics in Malaga, southern Spain, with data collection from 2001-2003
Participants	Inclusion criteria: 12/23 community clinics selected to balance neighbourhood SES (low, medium, and high). Women included if less than 15 weeks’ gestation and smoked at least 1 cigarette since knowing they were pregnant Exclusion criteria: not further specified. Recruitment: 12 clinics ‘randomly selected’, stratified by SES status of neighbourhood. 3 randomly allocated to each study arm, based on SES status (3 levels, low, medium, high: so 1 level each study arm). Clinics balanced across study arms Women identified in 1999 in a preconceptual program (2,932 women screened in 23 clinics-38% were smokers). 719 eligible smokers from the 12 clinics were invited, of whom 455 agreed to participate (63% participation). 132 women spontaneously quit smoking after baseline and 27 had a spontaneous abortion; both were excluded from the study. 296 women were randomised (C = 54, I1 = 71, I2 = 47, I3 = 124). Baseline characteristics: Mean cigarettes per day before becoming pregnant 20.6 (9. 58); Fagerstrom score: 4.78 (SD 5.38) 97.7% married. Education: 4% did not complete junior high school, 45% completed junior level only (9 years), 33% 12 years school, 17% university level. SES: 4.8% high, 24.6% medium/high, 53.4% medium/low, 17.1% low SES Progress+ coding: None.
Interventions	Control: Usual care. All 3 interventions were based on CBT, adapted to pregnant women taking into account factors important to women for smoking and quitting, but differ in intensity (frequency and duration). Intervention 1 (low intensity): 1 session 30 minutes by midwives who were trained in smoking cessation psychosocial education, provided with audiovisual materials and gave women a pamphlet. Delivered in 2nd trimester, usually before week 24. Included smokers and those who had spontaneously quit. Able to invite companions or people involved in pregnancy to session. Session covered basic smoking risks and benefits of quitting, motivational therapy and CBT for self-control to quit smoking, self-monitoring, developing alternative behaviours, stimulus control, setting a quit date and how to obtain social support. Intervention 2 (medium intensity): I1+ additional 3 group sessions × 90 mins over 4 weeks in 3rd trimester (weekly and then after 15 days) in clinic. Provided by midwife with additional training. Reviewed homework, introduced topic of day, set objectives and activity to complete before the following week. Recommended that by second week they abstain from tobacco. Only pregnant women invited to groups (6-10 women in each group), no partners. Audiovisual materials and self help guide to support sessions. Intervention 3 (high intensity): I1+5 × 90 mins weekly group sessions in 3rd trimester provided by clinical psychologist. Midwife present in sessions. Reviewed homework, set objectives and goals etc (similar to I2), counselled to quit smoking on 4th week of program. Used audiovisual equipment. CO monitoring and feedback provided in 2nd session with motivational interviewing. Included relapse prevention. Companions not included in group sessions Main intervention strategy: Counselling (multiple intervention) compared to usual care. Intervention 3 (high intensity) and control (usual care) compared in this review Intensity: Frequency (C = 0, I = 6); Duration (C = 0, I = 5). Usual care intensity: F = 0, D = 0 Intervention provided by dedicated study staff: Efficacy study
Outcomes	Self-reported mean cigarettes per day in late pregnancy*; Mean exhaled CO; Mean birthweight* Biochemically validated point prevalence abstinence rates not reported. Breastfeeding rates at 8 weeks postpartum reported
Notes	Report in Spanish.
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Clinics described as ‘randomly assigned’.
Allocation concealment (selection bias)	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	455 consented and 132 excluded as they spontaneously quit smoking, and further 27 excluded due to spontaneous abortion. Substantial attrition in this study (92% in I3): 296 randomised, 204 started intervention and 142 completed intervention and used in the analysis. Not able to be re-included as mean outcomes only reported (e.g. mean cigs/day, mean CO). Randomised : C = 54, I1 = 71,I2 = 47, I3 = 124. Started intervention: C = 54,I1 = 71, I2 = 12, I3 = 67 Completed intervention and analysed: C = 54, I1 = 71, I2 = 8, I3 = 9.
Selective reporting (reporting bias)	High risk	Biochemically validated smoking cessation rates, proportion of preterm births, and stages of change outcomes stated as primary and secondary outcomes and not reported
Other bias	High risk	Tried to balance women across study arms and clinics (40 per arm per clinic) but were unable to achieve this
Biochemical validation of smoking abstinence (detection bias)	Unclear risk	Exhaled CO validation measured but biochemically confirmed smoking cessation rates not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	States clinics were not aware of allocation.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessors blinded.
Incomplete implementation	Unclear risk	Only 8% completed the high and medium intensity interventions (group sessions)
Equal baseline characteristics in study arms	Unclear risk	Baseline characteristics not reported by individual study arm
Contamination of control group	Unclear risk	Cluster-randomised trial design minimises risk of contamination