Background: Methods used to develop existing core outcome sets relevant to maternal and neonatal health have not been fully evaluated. Objectives: To systematically review core outcome sets relevant to maternal and neonatal health; evaluate against minimum standards for development; and evaluate overlap between core outcome sets. Search strategy: Multi-faceted search of two core outcome set registers (COMET, CROWN) the ICHOM database of standard sets, and three electronic databases (MEDLINE, EMBASE, CINAHL) was conducted from inception to January 2020. Selection criteria: Published papers reporting completed core outcome sets relevant to maternal or neonatal health, for research or clinical use, were evaluated against COS-STAD minimum standards for development. Data collection and analysis: Descriptive statistics describe characteristics and results. Main results: Thirty-two papers relating to 26 core outcome sets were included (maternal: 18 papers: 17 COS; neonatal: 14 papers: 9 COS). Fifteen (58%) were published since 2017. No included COS met all minimum standards for development. All COS met the minimum standard for scope. Eighteen (69%) met all three minimum standards for stakeholder involvement. No included COS met all five minimum standards for consensus process. COS included between 6 and 56 outcomes. Two COS (8%) provided recommendations for how and when to measure outcomes. Conclusions: This is the first application of COS-STAD minimum standards relevant to maternal and neonatal health. Findings offer a baseline evaluation. There is an urgent need to address outcomes, measurement and timing in core outcomes to support harmonization between core outcome sets.