Methods	Prospective randomised controlled trial in 5 health centres of the same HMO in Los Angeles, 1985 -87
Participants	English-speaking women < 18 weeks’ gestation; still smoking >= 7 cigarettes a week (n = 323, 165 + 158, with losses due to termination (7 + 11); miscarriage (12 + 13); disenrolment or transfer to another HMO (20 + 18); leaving 126 + 116
Interventions	Control group: 2 page pamphlet on hazards of smoking and on the need to quit; 2 minutes discussion with a health educator (within a 45 minutes individual conference) ; advised of free 5 session smoking cessation program available through the HMO. Coverage in antenatal classes remained unchanged. Intervention group: as for the control group + first of series of 8 self-help booklets aimed to increase motivation for quitting; teach behavioural strategies for cessation and relapse prevention; 3 minutes introduction to these by health educator; asked to make a commitment to read the first one and list reasons for not smoking; others mailed weekly. Booklets were pregnancy-specific, multi-ethnic, and at a 9th Grade reading level. Theoretical basis - aimed to increase motivation and teach behavioural change strategies. Intensity rating: I = 3, C = 2
Outcomes	Smoking cessation validated with urine cotinine; birthweight; low birthweight; preterm birth (< 37 weeks); stillbirths
Notes	Process evaluation showed good implementation.
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	Unclear	No information
Allocation concealment?	No	The authors state that women had been randomised in advance of their visit. It was not clear how women were recruited to the study or gave consent for participation. The health educator turned over a ‘preassigned card’ to randomise women
Blinding? Women and clinical staff	No	The authors state that the health educator delivering the intervention was not aware of group allocation, but materials were provided to the experimental group at the clinic visit
Incomplete outcome data addressed? All outcomes	Unclear	Attrition I = 39/165, C = 44/158 not included in analysis (due to miscarriage, abortion or disenrolment from the HMO)
Free of selective reporting?	Unclear	None apparent.
Free of detection bias?	Yes	Biochemical validation by urinary cotinine levels.