Features of smoking cessation, alcohol reduction, and diet and physical activity interventions associated with changing behaviours during pregnancy: a systematic review of reviews

Systematic reviews of smoking, alcohol, diet and physical activity (PA) behaviour change interventions in pregnancy have high heterogeneity in effectiveness estimates for maternal behaviours and pregnancy outcomes, and it is unclear which features of interventions are integral to promoting effectiveness. This systematic review of reviews aimed to compare findings to identify any shared behaviour change techniques (BCTs), content, or delivery of interventions that may be associated with effectiveness across diet, physical activity, smoking and alcohol behaviours, and to identify intervention features showing promise in targeting one behaviour but have yet to be tested in addressing other behaviours. The search strategy covered reviews published between 2013 and 2025 and identified 66 reviews (9 smoking, 6 alcohol, 50 diet/PA, 1 smoking, diet, and/or PA). Diet/PA interventions should begin in the first trimester, run for a longer duration, and entail frequent engagement via a range of modalities in a supervised format (ideally from a specialist provider). Smoking intervention effectiveness was consistently associated with incentives and counselling. Brief interventions were consistently reported as effective interventions for alcohol use but there was a lack of standardisation in delivery. BCTs from the "goals and planning" and "feedback and monitoring" domains were routinely associated with effectiveness. Further research is required to explore intervention features that have shown promise in one behaviour but have yet to be tested for other behaviours, such as incentives in alcohol interventions.