Methods	Randomised controlled trial of ultrasound feedback and cognitive-behavioural modification, to support women to stop smoking in pregnancy Study conducted in the National University Hospital, Oslo, Norway (Europe), with recruitment from June 1990 to October 1991
Participants	Inclusion criteria: Pregnant women attending antenatal clinic for 18 weeks for ultrasound, and still smoking 10 cigarettes per day or more (heavy smokers) Exclusion criteria: Not further specified. Recruitment: Not stated how many women approached or eligible (1800 births/year, study over 15 months). 112 women randomised (C = 56, I = 56) Baseline characteristics: Mean cigarettes per day at 18 weeks’ gestation: C = 14.8, I = 12.5. Smoking partner: C = 80%, I = 74% Mean age: C = 28.4, I = 20.2. Progress+ coding: None.
Interventions	Control: Routine 18-week ultrasound and information on the negative effects of smoking and encouragement to quit, reinforced by a pamphlet, provided at the time of the ultrasound examination. Intervention: At the time of the 18 week ultrasound scan, offered the Windsor self-help manual (translated into Norwegian) describing a 10-day program which includes relapse prevention. During ultrasound (by midwife and obstetrician) women were given information about the negative effects of smoking. 2 weeks later women were sent an encouraging reminder and an appointment for an additional 32-week scan by an obstetrician, in which women were further encouraged to quit. A second reminder was sent 2 weeks later Main intervention strategy: Feedback (multiple intervention) compared to usual care. Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). Usual care intensity: F = 1, D = 1 Intervention provided by existing staff: Effectiveness study
Outcomes	Self-reported abstinence at delivery (late pregnancy*); self-reported reduction in smoking at birth* mean cigarettes per day at birth*. Stillbirths* reported in attrition and re-included in both numerator and denominator for this outcome
Notes	Process evaluation suggested that the acceptance of the manual was low (mean score 2. 6 on 7 point scale) and that it was staff involvement which had the most impact
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as “consecutively randomised”.
Allocation concealment (selection bias)	High risk	Women consecutively randomised into 2 groups.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition: one stillbirth in intervention arm excluded from analysis. 7 women who did not return questionnaires (C = 6, I = 1)were not included in the study report but have been re-included as continuing smokers in this review (C = 56, I = 55)
Selective reporting (reporting bias)	Unclear risk	Only smoking outcomes reported.
Other bias	Unclear risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	High risk	No biochemical validation.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind participants and providers to educational intervention and ultrasound. Although it is unclear if consent was sought so participants may have been blind
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	Low risk	No process evaluation reported but assume most women received manual and ultrasounds
Equal baseline characteristics in study arms	Unclear risk	Intervention group had significantly higher daily smoking on entry
Contamination of control group	High risk	Usual care providers offering intervention and control components