Outcomes in gestational diabetes Cochrane protocols and reviews before and after development of ‘standard outcomes’ by WOMBAT (WOMen and Babies health and well‐being: Action through Trials) were surveyed. An increase in ‘common’ outcomes (those prespecified by ≥50% of the protocols and reviews) over time was observed (2001–2009: 27 vs 2010–2014: 46). There were discrepancies in outcomes prespecified in reviews and reported by randomised trials. Efforts are needed to develop a core outcome set, to reduce research waste and improve health outcomes.