Methods	3-armed randomised controlled trial of 2 brief interventions to support women to stop smoking in pregnancy Study conducted in an inner urban setting, Toledo, Ohio (USA), with recruitment from December 1987 to March 1989
Participants	Inclusion criteria: Not specified. Exclusion criteria: > 28 weeks’ gestation. Recruitment: All 1,164 patients screened, 486 current smokers (42%). 293 refused or were ineligible (40% participation). 193 smokers randomised to study (C = 71, I1 = 52, I2 = 70). Baseline characteristics: Baseline smoking not reported. Mean age=22.6 (5.6), ranging from 15-43 years. 58% single, 70% white, 87% had not graduated from high school. Author describes population as “Typically low income, single and poor” Progress+ coding: Low SES.
Interventions	Control: Usual care not specified or assessed but “usual for physicians to address this issue with participants at least 1 prenatal visit”. Intervention 1: American Lung Association self-help booklet (with brief overview and explanation) emphasising behaviour modification skills, relation techniques and the support of significant others, and were given an opportunity to ask questions of the health educator. Progress reviewed with health educator at the second visit Intervention 2: Tailored educational videotape 6.5 minutes, potential fetal risks, benefits if mother quit + pamphlet on how to quit and opportunity to ask questions of the health educator. 1 month later they viewed a second 4 min video and the health educator was available to answer questions Main intervention strategy: Counselling (single intervention) compared to usual care. The control and intervention 2 (video-tape) are compared in this review Intensity: Frequency (C = 0, I = 3), Duration (C = 0, I = 2). Usual care intensity: F = 1, D=1 Intervention provided by dedicated project staff: Efficacy study
Outcomes	Biochemically validated smoking cessation ‘two or three weeks prior to delivery’ (late pregnancy*). Smoking reduction* and mean cigarettes/day*
Notes	Program was developed with input from a questionnaire (based on Health Belief Model) and open-ended questions about the advantages and disadvantages of smoking when pregnant from local population. Commentary on the contextual factors in the lives of indigent women which lead them to have different perceptions about the relative importance of smoking
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not reported.
Allocation concealment (selection bias)	High risk	Tossed die (allocation could therefore be changed). Method resulted in 3 unequal groups, so randomisation to only 2 groups for some of the study period, which was the control and intervention 2 (videotape) group, compared in this review
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition 44% (C = 46, I1 = 13, I2 = 25) . Reasons for attrition not reported. However all drop-outs treated as continuing smokers in this review
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)	Low risk	Smoking cessation was biochemically validated using exhaled CO (<= 7 ppm cut-off)
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	High risk	44% did not receive intervention.
Equal baseline characteristics in study arms	Unclear risk	Not reported.
Contamination of control group	Low risk	Specific educators providing intervention (pregnancy care providers not involved)