Randomised controlled trial of home based motivational interviewing by midwives to help pregnant smokers quit or cut down

OBJECTIVE: To determine whether motivational interviewing--a behavioural therapy for addictions-provided at home by specially trained midwives helps pregnant smokers to quit. DESIGN: Randomised controlled non-blinded trial analysed by intention to treat. SETTING: Clinics attached to two maternity hospitals in Glasgow. PARTICIPANTS: 762/1684 pregnant women who were regular smokers at antenatal booking: 351 in intervention group and 411 in control group. INTERVENTIONS: All women received standard health promotion information. Women in the intervention group were offered motivational interviewing at home. All interviews were recorded. MAIN OUTCOME MEASURES: Self reported smoking cessation verified by plasma or salivary cotinine concentration. RESULTS: 17/351 (4.8%) women in the intervention group stopped smoking (according to self report and serum cotinine concentration < 13.7 ng/ml) compared with 19/411(4.6%) in the control group. Fifteen (4.2%) women in the intervention group cut down (self report and cotinine concentration less than half that at booking) compared with 26 (6.3%) in the control group. Fewer women in the intervention group reported smoking more (18 (5.1%) v 44 (10.7%); relative risk 0.48, 95% confidence interval 0.28 to 0.81). Birth weight did not differ significantly (mean 3078 g v 3048 g). CONCLUSION: Good quality motivational interviewing did not significantly increase smoking cessation among pregnant women.