Systematic identification of existing core outcomes related to preterm birth and the development of a core outcome set for preterm birth in Aotearoa New Zealand.

Importance: Preterm birth is a leading cause of perinatal morbidity and mortality and a priority area for care improvement globally, including in Aotearoa New Zealand. To improve the efficiency and impact of preterm birth research and clinical care advancement, it is important to use standardized outcomes across studies and clinical sites. Objective: To identify existing core outcome sets related to preterm birth and use consensus methodology to develop a national core outcome set applicable for use in Aotearoa New Zealand. Methods: A systematic search identified established core outcome sets relevant to preterm birth. The core outcomes were reviewed, similar terms were merged, and outcomes irrelevant to preterm birth were excluded. The resultant outcomes were included in a three-round online Delphi survey involving people with lived experience, healthcare professionals, and researchers, with focussed recruitment of Māori, Pacific, and Indian participants. Outcomes were included if >70% of participants in each stakeholder group scored the outcome as critically important. Results: Eighteen established core outcome sets, containing 348 outcomes, were identified. Seventy-three distinct relevant outcomes were included for prioritization. Fifty-two participants, including 25 with lived experience, completed all rounds of the Delphi survey, with 15 outcomes included in a resultant preterm birth core outcome set. Interpretation: Core outcomes relevant to preterm birth were systematically identified. A national preterm birth core outcome set, informed by people with lived experience and perinatal healthcare professionals and researchers, was developed and will allow meaningful comparisons over time and across groups.