Does use of a carbon monoxide (CO) monitor in pregnancy promote smoking behaviour change? A qualitative exploration using the COM-B framework

Background Smoking in pregnancy has detrimental impacts on maternal and fetal health. The adverse outcomes attributable to smoking however, are reduced if women cease before 20-weeks gestation. Antenatal carbon monoxide (CO) monitoring could provide motivation for smoking behaviour change, but there is limited evidence on pregnant women’s perceptions of this intervention. Methods Women (n = 13) who smoked tobacco during pregnancy were recruited from an Adelaide hospital. They participated in two interviews, 4-weeks apart, using a CO monitor at both. Interviews were audio-recorded, transcribed and thematically analysed using the Theoretical Domains and COM-B frameworks. Results Analysis generated two sub-groups highlighting differing framework components: Decreased CO group (DCO, n = 7) and Increased CO group (ICO, n = 6), as determined by the CO reading at the second interview compared to the first. For both groups, using the CO monitor was understood as an education intervention increasing smoking impact knowledge. The DCO group used this knowledge to increase motivation via intention and goal formation to change smoking behaviour. They reported positive anticipation of repeat monitor use, and increased motivational conditions, reinforcement, optimism and belief about capabilities at the second interview. The ICO group however reported decreased motivation in response to increased knowledge, describing a combination of overwhelming emotional responses and cognitive overload that did not promote behaviour change. Conclusion Consistent CO monitor use may promote smoking decrease through pregnancy for some (only 2 women in the DCO group reported cessation), but not all women, suggesting antenatal CO monitoring should be carefully considered with reference to individual women’s needs and circumstances. Trial Registration Registered with the Australian New Zealand Clinical Trials (ANZCTR) Registry, Trial ID: ACTRN12621000670875 registered on 02 June 2021.