Hughes 2000.

Study characteristics
Methods	Study design: parallel‐group randomised controlled trial Setting: multi‐centre/hospitali Study duration: January 1996 to July 1999 Sample size calculation: yes, but not achieved: sample size estimation was based on what was considered to be a clinically significant difference between intervention and control in delta stage‐of‐change of 1.0. Standard assumptions of alpha (2‐tailed) = 0.05 and beta = 0.20 were used. The sample required was 107 patients per study arm. Although this target was reached for combined infertile and pregnant participants (N = 214), it was not attained for each independent sample,,as had been the original intention. The authors of this study state that it was stopped early due to funding issues, and that the study was underpowered
Participants	Number of participants randomised: 94; 47 in control, 47 in intervention (and 110 pregnant women) Baseline characteristics (mean ± SD) Control: age: 32.15 ± 4.55; lifestyle characteristics: number of quit smoking attempts: 3.40 ± 3.94; number of cigarettes: 13.80 ± 7.40; fertility characteristics: number of months infertile: 37.83 ± 29.40 Intervention: age: 32.13 ± 5.0; lifestyle characteristics: number of quit smoking attempts: 2.40 ± 2.10; number of cigarettes: 12.19 ± 6.81; fertility characteristics: number of months infertile: 38.08 ± 31.51 Baseline differences: no Inclusion criteria: all newly referred women with infertility who reported that they had smoked ≥ 3 cigarettes over the last 6 months Exclusion criteria: attending clinics for genetic counselling, habitual abortion, previously evaluated in consultation Phase of fertility treatment: pre‐treatment
Interventions	Control: routine care + unstructured minimal preconception lifestyle advice including assessment Description: standard care information about the impact of smoking on fertility and pregnancy + exhaled carbon monoxide measurements at enrolment, at 6 and 12 months Intervention: smoking Description: scripted motivational intervention with advice to quit smoking according to "stage‐of‐change" + "stage‐of‐change"–specific information booklet (5 prompt cards) + an offer for more in‐depth counselling at the hospital's smoking cessation clinic + assessment = exhaled carbon monoxide measurements at enrolment, at 6 and 12 months. Follow‐up: updated stage‐of‐change–oriented booklets as they progressed from one stage to the next Duration: 12 months Frequency: multiple contacts, not specified, probably baseline, at 6 and 12 months Setting: individual Mode of delivery: F2F + written
Outcomes	Reported behavioural changes in smoking: smoking self‐identified "delta stage‐of‐change" (difference in stage of motivation to change smoking behaviour) and rate of maintained smoking cessation at 12 months, measured with questionnaire (no further details)
Identification	Sponsorship source: Father Sean O’Sullivan Foundation, Hamilton Health Science Foundation, Ron Herkimer and Susan Sakowski, and Department of Obstetrics and Gynecology, McMaster University, Hamilton, Ontario, Canada Protocol available/trial registration: no Country: Canada
Notes	Study author was contacted for clarification on duration and frequency of intervention, baseline data, and outcomes (for delta stage‐of‐change, no SE, SD, or CI, and P values were reported; for rate of maintained cessation, no information on group with infertility was available and data from CO₂ exhaler as objective measure of smoking cessation were not reported). Study author replied that he was happily retired and does not have access to further information
Risk of bias
Bias	Authors' judgement	Support for judgement
Sequence generation	Low risk	Quote: "randomised using a computer‐generated, blocked schedule"
Allocation concealment	Low risk	Quote: "numbered, opaque, sealed envelopes" Comment: not specified whether envelopes were sequentially numbered, but likely to be at low risk of bias given that the envelopes were at least numbered, opaque, and sealed, and no baseline differences indicated issues
Blinding of participants and personnel All outcomes	High risk	Comment: as blinding was not described, study authors were contacted for the previous version of this systematic review Quote: "the primary care‐giver was unblinded because he had to do the intervention and the patient was unblinded because they were given the intervention". Comment: participants and personnel were aware of assigned intervention; deviations from the intended intervention could have occurred
Blinding of outcome assessors Objective outcomes	Unclear risk	Not applicable; no objective outcome measures in this study
Blinding of outcome assessors Patient reported outcome measures	High risk	Comment: outcome assessor is participant and is not blinded; reported behavioural changes in smoking are likely to be influenced. Having quit smoking is a more desirable answer
Incomplete outcome data	Low risk	Comment: as there was no description of completeness of reported data, study authors were contacted for the previous version of this systematic review. They reported that all patients were accounted for and were included in follow‐up
Selective outcome reporting	High risk	Comment: no study protocol was available to further verify selective outcome reporting. Study authors were contacted for the previous version of this systematic review on reporting of live birth. They reported that this information was not collected. this information could have been collected at 12‐month follow‐up. Secondary outcome (rate of maintained cessation): no data on infertile and pregnant women were provided separately. CO exhalation (to verify smoking cessation) was tested in all arms yet was not reported
Other sources of bias	Low risk	Comment in the previous version of this systematic review: "women in the control group were aware that their smoking status was to be measured several times throughout the study, the comparison is actually 'tailored advice + measurement versus measurement and therefore may not be an accurate assessment of tailored advice alone" This is now covered under indirectness (differences in comparison).