JMIR Publications

ABSTRACT

Background:

Pregnant women who live with a partner who smokes remain at high risk of secondhand smoke (SHS) exposure, a preventable cause of adverse pregnancy outcomes. Digital interventions offer a scalable route to promoting a smoke-free home (SFH), yet little is known about the mechanisms through which they act, and previous programs have rarely engaged the partner who smokes.

Objective:

This study aimed to explore participants' experiences of “First Breath,” a digital behavior change intervention to reduce prenatal SHS exposure, and to identify the mechanisms, barriers, and facilitators that shaped engagement with the intervention and behavior change.

Methods:

Pregnant women who did not smoke and were exposed to SHS at home, and expectant fathers who smoked, were randomized to “First Breath” or to a static online information page. “First Breath” provided knowledge and practical content to enhance motivation and self-efficacy to create an SFH, a personalized self-reported visual SHS exposure index, goal setting and action planning, text reminders, and guidance on nicotine replacement therapy (NRT) for temporary abstinence within the home. Women in both arms provided urine samples for cotinine analysis (a biomarker for SHS exposure), and biochemical feedback was provided for women in the intervention arm during the trial. Semistructured exit interviews were conducted with 27 of the 68 trial participants (15 women and 12 men; 13 intervention and 14 control) and analyzed using reflexive thematic analysis, with themes mapped deductively onto the capability, opportunity, motivation-behavior (COM-B) model.

Results:

Participants described the trial procedures and the intervention as acceptable. Exposure feedback was the most influential component and operated through 2 separate channels: the urinary cotinine results, described as more influential because they were external and biochemical, and the self-reported visual exposure index, which carried greater weight among the men, for whom it was the only personalized feedback available. Compared with the control arm, participants in the intervention arm reported broader knowledge acquisition, greater awareness, stronger attitudinal change, more couple communication, and more comprehensive behavioral adaptation. Change in the control arm was more limited and was prompted mainly by repeated questionnaire completion, which functioned unexpectedly as a behavioral cue. Most participants resisted NRT, engagement declined over time (most reported 3 to 6 entries in total), and travel to the study site for urine cotinine samples was the most significant external barrier.

Conclusions:

Personalized exposure feedback appears to be the principal mechanism through which “First Breath” promotes the reduction of prenatal SHS exposure, and should remain at the core of the program. A redesigned NRT component should be considered before a fully powered effectiveness trial. Clinical Trial: ClinicalTrials.gov NCT07003282; https://clinicaltrials.gov/study/NCT07003282