Methods	Cluster-randomised trial in Maastricht, The Netherlands. Feb-December 1996
Participants	Women using public health services, who smoke more than 1 cigarette per day, literate in Dutch, and gravidity less than or equal to 4. 80% eligible population approached. Participation rate 72% (n = 318). Mean cigarettes per day at intake I = 9.1, C = 7.7. Mean gestation at intake I = 12.4, C = 13.5. (ii) included women from trial (i) and spontaneous quitters; n = 253 (I) and 303 (C); 80% approached. 72% participation
Interventions	Control group received routine smoking cessation counselling and a folder about smoking cessation in pregnancy, (Both trials i and ii) Intervention group received routine care plus a minimum of2 counselling sessions from their midwife (who received a 3 hour training session on smoking cessation counselling and a booklet); a video; self-help guide; partner booklet and post-delivery booklet. Information was based on the stages of change model. Intensity rating: I = 4, C = 3
Outcomes	Self-reported quit attempts at 6 weeks’ postpartum, with urine cotinine biochemical validation in a small proportion of participants (n = 14). Self-reported partner smoking status. Detailed assessment of participant and midwifery views of interventions, including an analysis of psychosocial motives which are thought to be associated with implementation
Notes	Inconsistent information on gravidity criteria. Significant clustering identified at midwife level. The reported inter-cluster variance of 0.82 was used to derive ICC for adjusting reported outcome figures used in analysis. A separate detailed paper published on process evaluation issues which reports poor implementation in some aspects. Only 16.7% of women received the post-delivery booklet. No validation of longer-term self-reported smoking. Only 24.2% of chairs of midwifery agreed to approach midwives in their region to participate
Risk of bias
Item	Authors’ judgement	Description
Adequate sequence generation?	No	The first 40 practices (118 midwives) were selected, from 4 provinces, which were then matched (by location and level of urbanisation) into 2 pairs. All midwives in a province were allocated to either intervention or control care
Allocation concealment?	Unclear	Not reported.
Blinding? Women and clinical staff	No	Neither providers nor women were blinded for this counselling intervention
Incomplete outcome data addressed? All outcomes	Unclear	Not clear, figures are not consistent, as well as loss to follow up there are missing data for some variables When all drop-outs included as smokers 7-day abstinence I = 19% of 141 and C = 7% of 177, included in this analysis
Free of selective reporting?	Unclear	None apparent.
Free of detection bias?	No	Biochemical validation for a small sub-sample only.