Tappin 2015.

Methods	This 2‐armed randomised controlled trial, aimed to assess the efficacy of financial incentives added to routine pregnancy stop smoking services. This study was conducted in Greater Glasgow, Scotland, UK between December 2011 to February 2013 with follow‐up occurring in September 2013.
Participants	Inclusion criteria: Women were eligible if they were smokers with an exhaled CO level of at least 7 ppm, aged 16 years or more, less than 24 weeks pregnant, resident in NHS Greater Glasgow and Clyde, and able to understand and speak English for telephone consent. Exclusion criteria: Not stated. Recruitment: 612/1722= 35.5% women agreed to participate (C = 306 I = 306). Women were recruited through NHS stop smoking services. Baseline characteristics: Mean Fagerstrom score (C = 5.32 I = 4.85), partner smokes (C = 66.3 I = 59) Mean age at delivery (C = 27.66 I = 28.27). Progress + coding: None.
Interventions	Control: The control group was offered routine specialist pregnancy support by the stop smoking services, which included the offer of a face‐to‐face appointment to discuss smoking and cessation and, for those who attended and set a quit date, the offer of free NRT for 10 weeks provided by pharmacy services, and 4 weekly support phone calls. Intervention: The incentives group was offered the same routine support plus up to £400 of shopping vouchers (Love2shop) for engaging with stop smoking services or for quitting during pregnancy, or both. Intervention participants received £50 of vouchers if they attended their face‐to‐face appointment and set a quit date. Confirmed quitters were sent a further £50 voucher. 12 weeks after stopping smoking, women in the incentives group who were quitters at 4 weeks were contacted by stop smoking services (routine practice) and, if confirmed to be abstinent CO breath test result < 10 ppm), were sent a £100 voucher. A research nurse visited self‐reported quitters to collect a CO level, and saliva and urine for cotinine estimation. Women in the incentives group who were confirmed as abstinent by the CO breath test (< 10 ppm) were sent a final £200 voucher. Main Intervention strategy: Incentives (single) v UC Intensity: Frequency (C = 0 I = 4) Duration (C = 0 I = 4).
Outcomes	Cotinine verified cessation at 34‐38 weeks' gestation*, self‐reported quit at 6 months postpartum*, preterm birth*, mean birthweight*. Stillbirths and miscarriages combined so not included in this review. Engagement. Cost‐effectiveness.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	The Glasgow Clinical Trials Unit embedded the randomisation in the trial database using randomised permuted blocks, with a block length of 4, thus facilitating equal distribution of clients between the interventions.
Allocation concealment (selection bias)	Low risk	Allocation was concealed from staff and clients until after consent and recruitment.
Incomplete outcome data (attrition bias) All outcomes	Low risk	No evidence of unequal attrition in study arms and ITT analysis was used for missing data. 15% were lost to follow‐up and were counted as smokers.
Selective reporting (reporting bias)	Low risk	Both primary and secondary outcomes are reported.
Other bias	Low risk	No other bias detected.
Biochemical validation of smoking abstinence (detection bias)	Low risk	Smoking is biochemically validated, with cotinine verified cessation through saliva (< 14.2 ng/mL) or urine < 44.7 ng/mL
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not feasible to blind participants and providers to this intervention.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Helpline staff, who ascertained the primary outcome, self report of smoking status in late pregnancy, were blind to allocation status.
Incomplete implementation	Unclear risk	15% were lost to follow‐up and were counted as smokers.
Equal baseline characteristics in study arms	Low risk	Baseline characteristics appear even in both groups.
Contamination of control group	Low risk	Incentives were the main intervention component, therefore contamination more likely.