Ershoff 1999 (AvB).

Methods	3‐armed randomised controlled trial of interactive computer program and telephone counselling to support women to stop smoking in pregnancy. Study conducted in a large group model managed care organisation in Los Angeles, California (USA) with recruitment from November 1996 to June 1997.
Participants	Inclusion criteria: Smokers were identified at first visit as women who self‐report "smoking now", "smoke but have cut down since pregnancy", or "smoke from time to time". Exclusion criteria: < 18 years of age, > 26 weeks' gestation, do not speak English, or smoked less than 7 cigarettes pre‐pregnancy. Recruitment: Researchers attempted to phone 931 women. 150 could not be contacted, 90 refused to be interviewed, 158 were not eligible and 34 were excluded as they experienced miscarriage (n = 34). 390/458 women (82%) agreed to participate (C = 131,I1 = 133, I2 = 126). Baseline characteristics: Pre‐pregnancy mean cigarettes per day: C = 17.1 (9.7), I1 = 17.6 (9.8), I2 = 16.3 (7.6). Mean cigarettes per day at intake: C = 6.6(7.3), I1 = 6.7(6.5), I2 = 6.3(6.5). 60% white, approximately 50% college educated, with a mean age of 29.4. Mean cigarette/day at first visit = 6.6. Progress + coding: None.
Interventions	3 interventions, based on stages of change model. A: Control: Received a 32‐page self‐help booklet "living smoke‐free". B: Intervention 1 (interactive computer program‐IVR): received the same self‐help booklet and had access to a computerised interactive telephone support system, which provided customised messages from a voice model. Participants responded to questions using a touch‐tone keypad. C: Intervention 2 (MI): received the same self‐help booklet and 4‐6 x 10‐15 min telephone counselling sessions by nurse educators trained in MI. A personalised postcard sent to reinforce verbal communication. Main intervention strategy: Health education (tailored intervention) compared to a less intensive intervention (self‐help booklet). This study ID compares arms A and B, see Ershoff 1999 (AvC) for A and C. Intensity: Frequency (C = 2, I = 2), Duration (C = 1, I = 1). Intervention provided by study staff: efficacy study.
Outcomes	Biochemically validated smoking cessation at 34 weeks' gestation (late pregnancy*). Mean cigarettes per day*. Baseline mental health index and Cohen's perceived stress scale. Number of quit attempts and movement in stages of change.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Described as "random assignment"
Allocation concealment (selection bias)	Unclear risk	No information.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Attrition 58/390 (14.87) due to abortion (n = 31), disenrolment from health plan (n = 22) and preterm birth less than 32 weeks (n = 5). Lost to follow‐up not included as continuing smokers in analysis as attrition due to medical reasons and moving not re‐included in this review, and attrition from each study group not reported separately. 332 included in analysis (C = 111, I1 = 120, I2 = 101).
Selective reporting (reporting bias)	Unclear risk	Results were difficult to interpret.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Low risk	Biochemical validation by urinary cotinine levels (< 80 ng/mL).
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Authors state that care providers were blind to group allocation. Educational intervention so blinding women not feasible.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported
Incomplete implementation	Low risk	Good process evaluation of each of the methods. 79.2% received at least 1 call. Mean 4 calls lasting 12 mins each.
Equal baseline characteristics in study arms	Low risk	No significant differences reported.
Contamination of control group	High risk	11% control group received individual smoking cessation counselling as they were classified as high‐risk patients.