Behaviour model integrated by protection motivation theory and information–motivation–behavioural skills model applying in pregnancy weight management (PrInMAMa): a study protocol for a randomised controlled trial in China

INTRODUCTION: Excessive gestational weight gain poses a significant threat to maternal and child health. The healthy behaviour theory has been increasingly applied to weight management during pregnancy, but research is still insufficient. The successful application of the protection motivation theory (PMT) and the information–motivation–behavioural skills (IMB) model in the field of healthy behaviour laid the foundation for this intervention study. The overall aim of this study is to test the effectiveness of interventions based on the behaviour model integrated with the PMT and IMB model (PMT–IMB model) on weight management and provide feasible methods for weight management during pregnancy. METHODS AND ANALYSIS: This prospective, single-centre, randomised controlled trial involves two steps. First, based on the PMT–IMB model, evaluation tools and intervention materials will be developed. Second, more than 800 women in the first trimester of pregnancy will be randomly assigned to two groups and will be followed until 1 week after delivery. The control group will receive standardised antenatal care (ANC), whereas the experimental group will receive both standardised ANC and interventions based on the PMT–IMB model. After three surveys (at enrolment, at 28 weeks of gestation, and on the day of hospitalisation for delivery), primary outcomes (scores of the subscales of the PMT–IMB model, scores of the pregnancy weight management strategy scale, and gestational weight gain) and secondary outcomes (pregnancy outcomes and pregnancy complications) will be obtained. Differences in outcomes between the two groups will be analysed to evaluate the effectiveness of the intervention. ETHICS AND DISSEMINATION: The study protocol has been approved by the ethics committee of Nanjing Medical University. All participants will sign an informed consent form prior to enrolment. The findings of the study will be published in peer-reviewed journals and presented at conferences. TRIAL REGISTRATION NUMBER: ChiCTR2100043231