["Health Expectations, Volume 29, Issue 4, August 2026. ", "\nABSTRACT\n\nIntroduction\nPatient and public involvement and engagement (PPIE) is increasingly recognised as important in health care research, yet reporting of how involvement is undertaken and how it informs intervention development remains inconsistent. In maternal health, information about antenatal vaccination is required early in pregnancy, highlighting the value of involving parents and communities in shaping how such information is developed and shared. This paper describes the use of Parent, Patient and Public Involvement and Engagement (PPPIE) to inform the development of an intervention to support antenatal vaccine uptake in Northern Ireland (NI).\n\n\nMethods\nInvolvement and engagement activities were embedded during the intervention development phase and informed by established guidance for inclusive practice. Partnerships were formed with a Maternity Service Liaison Committee (MSLC), Sure Start programmes in areas of social disadvantage and an outreach antenatal clinic serving an East Timorese community. Engagement approaches were adapted to each setting and included facilitated discussions, written feedback and digital tools to support participation. Trusted intermediaries and translators were used where appropriate and activities were documented to support reflection and transparency.\n\n\nResults\nInput from parents and community members informed the content, timing and presentation of antenatal vaccine information within the developing intervention. Contributors highlighted the importance of clear, plain language information early in pregnancy and the value of tailoring information to different needs. Working through established community networks supported engagement with groups who are often underrepresented in research. Feedback was shared with contributors using a ‘you said, we did’ approach to demonstrate how their input influenced the developing intervention.\n\n\nConclusions\nThis paper provides a practical case study of how PPPIE can be embedded within antenatal intervention development. By describing approaches and learning, it contributes to the evidence base on involvement and engagement in maternal health research and offers insights for others seeking to undertake similar work in maternal health.\n\n\nPatient or Public Contribution\nParents and members of the public were involved through PPPIE activities undertaken during the design and development of the intervention. Their input informed the content, timing and presentation of antenatal vaccine information and supported refinement of the intervention during development.\n"]