Cooper 2014.

Methods	Country: UK Setting: hospital (antenatal clinic) Type: RCT
Participants	1051 smoking 12‐ to 24‐week pregnant women who currently smoke 5 or more cigarettes per day and who smoked at least 10 cigarettes per day before pregnancy
Interventions	Intervention: biochemically validated smoking cessation with transdermal nicotine patches (15 mg per 16 hours) for 4 weeks, followed by another 4 weeks if abstinent Control: visually identical placebo
Outcomes	Child exposure: maternal self‐reported prolonged and total abstinence from smoking validated by exhaled CO and/or salivary cotinine Child illness: birth outcomes, infant impairment, infant respiratory symptoms up to age 2 Target behavioural change: smoking cessation
Type of intervention	Well‐child (antenatal health check)
Notes	Conflict of interest: NM reports personal fees from Novartis and personal fees from Elsevier, outside of the submitted work; TC reports personal fees from Pierre Fabre Laboratories, France, outside the submitted work. Source of funding: HTA programme project number 06/07/016
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Internet‐based randomisation that was stratified by recruiting site
Allocation concealment (selection bias)	Unclear risk	All pharmacists, research staff, and trial participants blinded to treatment allocations, but unclear about allocation concealment
Incomplete outcome data (attrition bias) All outcomes	Low risk	By 2‐year follow‐up, 14% in NRT group and 15% in control group dropped out.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Double‐blind and objective measure
Other bias	High risk	• Smoking data were not sought from all participants at predetermined time points, but were obtained opportunistically at multiple, different times between 8 and 54 months after childbirth, rendering smoking behaviour data difficult to interpret. • Smoking outcomes at 2 years were self‐reported, which may lead to bias; furthermore, these outcomes were not assessed in about 40% of participants.