Methods	Randomised controlled trial (pilot study) of home based motivational interviewing to support women to stop smoking in pregnancy Study conducted in a Glasgow Hospital, Scotland (UK), with recruitment from March to May 1997
Participants	Inclusion criteria: Women who identified as smokers on a questionnaire at antenatal clinic booking Exclusion criteria: Not further specified. 133/393 (34%) women screened identified as smokers and 100/133 (75%) agreed to participate and were randomised (C =5 0, I = 50) Baseline characteristics: Mean cigarettes per day pre-pregnancy C = 18.1, I = 19.6; current mean cigarettes per day C = 13.2, I = 14.8; partner smoking: C = 82%, I = 90%; Mean cotinine C = 126 ng/mL, I = 136 ng/mL Mean age: C = 25.9, I = 26.6; 76% ‘severely deprived’ participants Progress+ coding: Low SES.
Interventions	Control: Received usual advice from their prenatal providers, which should include information about smoking Intervention: Received 2-5 motivational interviewing sessions (mean 2.6 hours), based on stages of change, in the clients’ home conducted by a midwife with 3 weeks training in smoking cessation counselling Main intervention strategy: Counselling (single intervention) compared to usual care. Intensity: Frequency: (C = 0, I = 4), Duration (C = 0, I = 4). Usual care intensity: F = 1, D = 1 Intervention provided by dedicated study staff: Efficacy study
Outcomes	Biochemically validated smoking cessation at >=27/40 (late pregnancy*) Mean birthweight*, preterm births*, stillbirths*. Ranking interviews measured movement around the ‘cycle of change’ Detailed evaluation of participant and midwifery views of interventions
Notes	SDs for mean birthweight were not reported, therefore we calculated a mean SD from 13 studies with available birthweight SDs (578) to include in this review, as recommended by the cochrane handbook
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Random numbers stratified by deprivation.
Allocation concealment (selection bias)	Low risk	Group allocation by telephone.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low attrition (2%). Some missing data for cotinine validation. Smoking outcome results reported for all of those randomised, and those with missing data counted as continuing smokers in this review
Selective reporting (reporting bias)	Low risk	Detailed outcomes reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Low risk	Serum cotinine levels measured.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind participants and personnel to counselling intervention
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	Unclear risk	Good process evaluation of implementation quality according to rating tool, showed 79% of women in the intervention group received at least 2 counselling sessions
Equal baseline characteristics in study arms	Low risk	No apparent difference.
Contamination of control group	Low risk	Specific counsellors provided intervention at home so contamination unlikely. Less than 20% of the control group recalled being given smoking information at the time of booking