McBride 2004.

Methods	Randomised controlled trial Study dates: 1996‐2001 Army Medical Center, USA; random assignment
Participants	385 pregnant women, 44% already abstinent, mean age 24 yrs; 96% married; mean number of cigarettes smoked per day before pregnancy: 13 Partners = mean age 25, 46% non‐smoking partners
Interventions	(1) Women‐only: self‐help guide, late‐pregnancy relapse prevention kit, 6 counselling calls (n = 192) (2) Partner‐assisted: women‐only intervention + PS intervention (booklet, companion video, 6 counselling calls) (n = 193)
Outcomes	Self‐reported abstinence. Saliva samples collected by mail at 28 weeks pregnancy and 12 months postpartum but not used to confirm self‐report. 6‐month and 12‐month postpartum point prevalence abstinence used in MA PIQ and general emotional and instrumental support assessed
Notes	For purpose of this analysis, we did not use a usual‐care group (n = 118) Partners who smoked were given self‐help cessation guides, free nicotine patches, and counselling. Funded by a grant from the National Cancer Institute (CA76945) Author declarations: not reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised, method not described, stratified by smoking status
Allocation concealment (selection bias)	Unclear risk	Method not specified
Blinding of outcome assessment (detection bias) All outcomes	High risk	Quote: "Intervention outcomes were based on self‐reported abstinence" despite the fact saliva samples were collected. Plus the groups had differential levels of support (due to the additional partner support in the intervention group). We therefore judge this to be at high risk of detection bias.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Participants lost to follow‐up counted as smokers; at 12 months, 31 of 192 lost to follow‐up in group 1; 46 of 193 lost to follow‐up in group 2. Loss to follow‐up low and similar between groups