Methods	3-armed randomised controlled trial of counselling and social support interventions to support women to stop smoking during pregnancy and prevent relapse post-partum The study was conducted in Womack Army Medical Centre at Fort Bragg in Feyettville, North Carolina (USA) from 1996 to 2001
Participants	Inclusion criteria: <= 20 weeks pregnant, >= 18 years of age, current smokers or recent quitters (i.e., were smokers in the 30 days prior to pregnancy but not smoking at intake), living with an intimate partner, and willing to have the partner contacted for participation in the study Exclusion criteria: Not further specified. Recruitment: 6156 woman screened at first prenatal clinic appointments were sent introductory letters with a toll-free number to call to decline contact. 997 pregnant smokers or recent quitters underwent further screening and 625 eligible women were randomised Baseline characteristics: Active smokers (C = 91, I1 = 87, I2 = 89). Recent quitters (C = 107, I1 = 105, I2 = 104). Current mean cigarettes per day 6 (SD 5). 52% had a partner who smoked Mean age 24 years; Household income >= 20000 $US 44%; >high school 52%; 96% married; 77% white Progress+ coding: none.
Interventions	Control: ‘Usual care’ where women received provider advice to quit smoking at the first prenatal visit and were mailed the American Cancer Society’s self-help guide, “Make Yours a Fresh Start Family,” written at the fifth-grade reading level and designed for pregnant women Intervention 1 (woman only): Control plus late pregnancy relapse-prevention kit (a booklet and gift items) and 6 counselling calls (3 in pregnancy and 3 in postpartum) initiated by a health advisor, who used a standardised protocol based on motivational interviewing techniques. All intervention contacts were completed by 4 months postpartum. Prenatal calls were timed to occur in each trimester and emphasised using self-help materials to take stage-appropriate steps towards cessation or to develop skills for remaining abstinent. Postpartum calls were timed to occur at monthly intervals and emphasised skills for remaining abstinent in the transition from pregnancy to parenting Intervention 2 (partner-assisted group): Woman only intervention plus a PA adjunct, in which the smoker described how her partner could be a coach to build and maintain the confidence she needed to quit smoking. An “It Takes Two” booklet and companion video were developed to guide couples in discussing support behaviours related to the woman’s smoking. Partners received 6 separate calls (3 in pregnancy and 3 postpartum) from the woman’s health advisor. These calls were made separately to the 2 individuals (pregnant woman and partner) and guided by a motivational interviewing protocol similar to that used for counselling the women. The second and fourth calls to the couple focused on developing a written agreement regarding helpful partner support behaviours. Partners who smoked were given self-help cessation guides, free nicotine patches if needed, and stage-appropriate counselling Main intervention strategy: Social support (multiple intervention) compared to a less intensive intervention. Intervention 2 compared to control in this review Intensity: Frequency (C = 2, I = 6); Duration (C = 1, I = 5). Estimate as duration of calls not reported Intervention provided by dedicated project staff: efficacy study
Outcomes	Self-reported point prevalence abstinence at 28 weeks pregnancy (late pregnancy*), relapse prevention at 28 weeks pregnancy (late pregnancy*), continued abstinence of combined spontaneous quitters and smokers at 2 (0-5*), 6 (6-11*) and 12 (12-17) months postpartum Partner cessation and perceived support were reported.
Notes
Risk of bias
Bias	Authors’ judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Reported as ‘stratified by smoking status, partners smoking status and partners willingness to be involved and randomised to one of 3 conditions’
Allocation concealment (selection bias)	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	42 (7%) women who miscarried were excluded resulting in a sample of 583 (C = 198, I1 = 192, I2 = 193). An ITT approach was used, in which all randomised women (other than those who had miscarried)were included in the final analysis as continuing smokers. Drop out rates did not differ significantly across groups
Selective reporting (reporting bias)	Low risk	All primary outcomes appear to be reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	High risk	Self-reported smoking status only.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind participants to social support intervention, requiring partner consent
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Not reported.
Incomplete implementation	High risk	Partner participation decreased steadily throughout the trial
Equal baseline characteristics in study arms	Low risk	Baseline characteristics appear equal.
Contamination of control group	Low risk	Care providers not providing intervention.