Effectiveness of motivational interviewing in influencing smoking cessation in pregnant and postpartum disadvantaged women.

Introduction: Systematic assessments of Motivational Interviewing (MI) in smoking behavior have been rare to date. This study aimed to determine whether an integrated approach, involving staff training in MI techniques, was sufficient to affect change in smoking status or intensity in low-income pregnant and postpartum women.

Methods: Overall, 500 consecutive smokers were recruited at first prenatal visit to public antenatal clinics. Following staff training, 500 more were recruited (intervention group). Data were recorded at 28-32 weeks gestation, after birth, at 3-4 and 7-9 months postpartum. The primary outcome measure was self-reported continued abstinence from smoking verified by urinary cotinine analysis. Changes in smoking intensity were also measured.

Results: There was no significant difference in the proportion of smokers in the intervention and control groups who reported stopping smoking at 28-32 weeks gestation (8.2% vs. 8.8%; p = .73), 1 week after birth (8.6% vs. 11.4%; p = .14), 3-4 months after birth (5.8% vs. 4.8%; p = .48), or 7-9 months after birth (5.2% vs. 4.0%; p = .36). Although more cases were nonsmoking at the second visit, 14.8% [95% CI = 11.8-18.5] vs. 13.1% controls [95% CI = 10.3-16.6], this was not statistically significant.

Conclusions: MI delivered at a number of time points during pregnancy and up to 9 months postpartum failed to affect quit rates. It may have had a small effect in preventing relapse among spontaneous quitters in late pregnancy though the validity of this remains uncertain.