Albrecht 2006 (AvB).

Methods	3‐armed randomised controlled trial evaluated the short‐ and long‐term effects of 2 smoking cessation strategies tailored to support pregnant adolescents to attain abstinence in pregnancy and maintain abstinence postpartum. The study was conducted in 5 hospital‐based and 2 community‐based prenatal clinics in Pittsburgh, Pennsylvania, USA. Years of data collection not reported.
Participants	Inclusion criteria: 'Pregnant teens' aged 14 to 19 years; 12 to 28 weeks' gestation; able to read, write, and understand English; smoking at least 1 cigarette per day; single marital status; having no previous live births; and capable of being reached by telephone. Exclusion criteria: pregnancy complications (i.e. bleeding or preterm labor) or required confinement to home by their physician. Recruitment: During prenatal assessment, adolescents self‐reporting smoking were invited to participate in study. Those expressing interest signed a consent form to allow the research team to contact them. Expressions of interest also advertised through flyers and brochures. 470 screened; 142/224 (63%) eligible women randomised (C = 50; I1: (TFS) = 47; I2: (TFS + B) = 45. Baseline characteristics: Number of cigarettes per day before pregnancy: Control 15.75 (10.38); I1: (TFS) 14.08 (7.22); I2: (TFSB) 14.62 (9.72). Fagerstrom dependence score: Control 3.38 (2.05); I1: (TFS) 3.44 (1.79); I2: (TFSB) 3.68 (1.89). Progress + coding: Low SES, Low educational attainment, low social capital (single) and young age (< 20 years).
Interventions	A: Control: UC that all teens would typically receive from a healthcare provider throughout their pregnancy. Smoking during pregnancy was addressed in the clinic by giving the teens educational materials on this subject during the initial prenatal visit. In this study, this material was explained and distributed to the participants by a research team member during the initial assessment. The meetings lasted 45‐60 mins and occurred at 1 of the AN clinics or centrally located community site. During the meeting, addresses and telephone numbers of the control group participants were updated after completion of the assessment. Prior to leaving the meeting, participants were informed of the date and time of their next assessment. Participants also received an attendance incentive (e.g. lipstick, nail polish). If the participant had delivered, the attendance incentive was a baby item. B: Intervention 1 (TFS): The TFS intervention consisted of an 8‐week group program designed to promote and maintain smoking abstinence based on the Cognitive Behavioral Theory, with modification that incorporated developmental components of Jessor’s Problem Behavior Theory, including a peer buddy and a peer co‐leader for peer modelling and sanctioning on smoking. Information pertinent to pregnancy and smoking was provided at the beginning of the 8‐week program. C: Intervention 2 (TFS‐B): The TFS‐B group received the same 8‐week programming, but participants were required to bring a non‐smoking female of a similar age as their buddy to the sessions. The role of the buddy was to reinforce smoking cessation strategies and to provide social support to the participant throughout the study. Main intervention strategy: Social support (multiple intervention) compared to a less intensive intervention. The control group and TFS‐B are compared in Albrecht 2006 (AvC) Intensity rating: Frequency (C = 2, I = 6); Duration (C = 3, I = 6). Provided by dedicated project staff: efficacy study.
Outcomes	Biochemically validated point prevalence abstinence 8 weeks (late pregnancy*) and 1 year (6‐11 months post partum*) after the intervention.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Consenting adolescents were assigned randomly to 1 of 3 group assignments (TFS, TFS‐B, or control) by a computer algorithm with a permutated block design, stratified by entry site.
Allocation concealment (selection bias)	Unclear risk	Not reported.
Incomplete outcome data (attrition bias) All outcomes	Low risk	High attrition: C = 60% (i.e. 40% did not complete 1 yr follow‐up), TFS = 55%, TFS‐B = 53%. Participants included in primary aim analysis pertaining to randomised treatment assignment, regardless of adherence to study treatment (ITT analysis).
Selective reporting (reporting bias)	Low risk	Primary outcomes reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Low risk	Biochemical validation of self‐reported smoking status (point prevalence abstinence) using salivary cotinine (> 10 ng). Women reporting less than 1 cigarette per day with salivary cotinine 10‐15 ng had salivary nicotine assessment to rule out environmental exposure, and were classified as smokers if that test was > 5 ng.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants and providers unlikely to be blinded to this educational intervention.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Blinding of outcome assessor not reported.
Incomplete implementation	High risk	Process evaluation showed poor implementation with almost 50% participants not completing study.
Equal baseline characteristics in study arms	Low risk	Baseline characteristics appear equal.
Contamination of control group	Low risk	Intervention provided by research team.