BACKGROUND-AIM:
Reducing smoking during pregnancy is a policy priority in Australia where evidence-based guidelines have been available since 2008, yet implementation is inconsistent. The MOHMQuit (Midwives and Obstetricians Helping Mothers to Quit smoking) program was developed to address this. MOHMQuit is a complex systems-change intervention which was co-designed using the Behaviour Change Wheel method. It has clinician, leader and systems elements, aiming to improve provision of guideline-recommended smoking cessation support (SCS) to pregnant people who smoke. The reasoning underpinning the intervention is that the MOHMQuit intervention strategies, co-designed with health professionals, will address identified barriers to providing support. This will result in increased capability of health professionals and maternity services to provide SCS, with increased support offered. This will in turn result in increased smoking cessation by pregnant people.

METHODS:
The MOHMQuit implementation trial used a pragmatic cluster-randomised stepped-wedge design with nine public maternity services in NSW, Australia, as the cluster units. The trial was conducted between May 2022 and December 2024. Multiple data sources were used (postpartum women were interviewed; clinicians were surveyed at baseline and six months later; and data on antenatal records were extracted from the electronic medical record (EMR)), to assess impact on: 1. Clinicians knowledge, skills, confidence and attitudes (mediators of change); 2. Provision of SCS to pregnant people; 3. Cessation outcomes.

RESULTS:
MOHMQuit significantly reduced the barriers experienced by health professionals in providing smoking cessation support, with statistically significant improvement across 17 of the 22 mediators, and large effect sizes found. There were significant improvements in provision of multiple components of SCS as documented in the EMR and as self-reported by clinicians. Significant improvements in cessation were not demonstrated, however many point estimates suggested a positive effect of the intervention. The lack of statistical significance may in part be due to lower recruitment of women than anticipated, resulting in the study being underpowered for this outcome. Strengths of the study include that it was a real-world trial, included all women who smoked at the beginning of pregnancy and birthed at the study sites, regardless of their motivation to quit, and used multiple data sources to assess the impacts.

CONCLUSIONS:
Overall, the results are encouraging in demonstrating a significant improvement in maternity service capability and provision of SCS to pregnant women. The careful, theoretically-informed co-design process ensured the intervention strategies addressed many of the barriers clinicians experience in providing SCS. The systems-change approach was key to making some progress in this intractable problem area.