Effect of theory-based health education intervention in improving exclusive breastfeeding intention among working mothers: a study protocol for a cluster randomised controlled trial

Despite global efforts, exclusive breastfeeding (EBF) rates remain a concern. Studies have shown that prenatal intention strongly influences subsequent breastfeeding practices. Consequently, an intervention module to improve exclusive breastfeeding intention is necessary. This study utilised the Theory of Planned Behaviour (TPB) as the theoretical framework for the intervention, as the factors influencing EBF intention are consistent with TPB constructs: attitude toward the behaviour, subjective norm, and perceived behavioural control. The intervention module was systematically developed using the Kemp Instructional Design Model. The module incorporated structured educational content, guided practice, and practical problem-solving strategies aligned with these constructs to strengthen mothers’ intention to practice exclusive breastfeeding. This study aimed to develop, validate, and evaluate a theory-based intervention module to improve EBF intention among working mothers in Malacca, Malaysia. A cluster randomised controlled trial (cRCT) was conducted to assess the intervention’s impact on knowledge, attitude, subjective norm, perceived behavioural control, EBF intention and proportion of EBF among the targeted population. This two-arm, parallel cRCT allocated pregnant women to either the intervention or control group by cluster at a 1:1 ratio, with each cluster defined as a government health clinic. This study was conducted over a 30-month period, encompassing planning, theory-based module development, implementation, and evaluation of effectiveness. All pregnant women who met the pre-defined inclusion criteria were included. A total of 216 participants were required for hypothesis testing. The primary outcome was EBF intention, and the secondary outcomes were knowledge, attitude, subjective norms, and perceived behavioural control regarding EBF, which were measured at baseline, 1 month, and 4 months postnatally. The proportion of EBF, however, was assessed at 6 months postnatally. This study was the first trial to assess the effectiveness of a theory-based health education intervention in improving EBF intention among working mothers in Malaysia. Furthermore, this study provided evidence on the effectiveness of the intervention delivered throughout both the antenatal and postnatal periods within this region. This study protocol was approved by the Medical Research and Ethics Committee, Ministry of Health Malaysia (NMRR ID-24-02852-NQU (IIR) on 23 December 2024. Amendment of the study protocol was approved on 15 December 2025. Thai Clinical Trials Registry, TCTR20250116001. Registered on 16 January 2025.