Introduction Screening to identify traumatic births and childbirth-related post-traumatic stress disorder (CB-PTSD) is critical for reducing the global burden of maternal mental health challenges. Despite this, no brief, validated tools exist for international use. This study therefore developed and validated a short version of the City Birth Trauma Scale (City BiTS) to provide a brief, globally relevant screening tool. Methods The City BiTS-Short was developed in three stages. In stage 1, exclusive lasso statistical analyses were conducted on survey data of 11 302 postpartum women in 31 countries to identify the most effective items for the City BiTS-Short, ensuring all four CB-PTSD symptom domains were represented. In stage 2, stakeholder reviews were conducted with researchers, health professionals (midwives, health visitors, psychiatrist, psychologist) and representatives of women who experienced traumatic birth. In stage 3, the City BiTS-Short was finalised and psychometric properties examined across diverse geographical settings. Results The City BiTS-Short comprises one item assessing traumatic birth and four items assessing CB-PTSD symptoms: re-experiencing, avoidance, negative cognitions and mood and hyperarousal. The scale had strong psychometric properties, including good internal consistency (α=0.78) and high correlations with the original City BiTS (r=0.90), birth trauma ratings (r=0.50), distress (r=0.56), impairment (r=0.47) and CB-PTSD diagnoses (r=0.54). It identified 90% of participants with a CB-PTSD diagnosis. Women who had operative births (F(3,2174)=127.38, p<0.001), maternal complications (F(2,2163)=212.84, p<0.001), infant complications (F(2,1100)=138.93, p<0.001) or depression (t(3209.5)=−30.96, p<0.001) had higher scores. Psychometric properties were consistent across most international contexts, with stakeholders affirming its utility. Conclusion The City BiTS-Short offers a brief, validated screening tool for identifying birth trauma and CB-PTSD symptoms. Its widespread adoption can enhance early detection and support for women, potentially reducing the global burden of birth trauma and improving maternal mental health outcomes worldwide. Further research is needed to explore its use in specific contexts.