Equal-contribution authorship, in which two or more authors are designated as having contributed equally, is increasingly common in scientific publishing. Using approximately 480,000 tagged records from PubMed and PMC (2010-2024), we examine temporal trends, journal-level patterns, geographic distributions, and byline positions of equal-contributing authors. Results show a sharp rise after 2017, with both high-output mega-journals and smaller, discipline-specific journals contributing to the growth. Journal-level analysis indicates a median increase in the share of tagged articles from about 19% in 2015 to over 30% in 2024, with some journals exceeding 50%. Geographically, China accounts for the largest share (40.8% of fractionalized contributions), followed by the United States (15.2%) and Germany (5.2%). Normalizing to 2015 baselines, China shows a 13.1x; increase by 2024, while even the slowest-growing countries more than tripled their levels. Analysis of normalized byline positions shows that equal-contribution designations are concentrated near the first-author position, with fewer cases in middle or last positions. These findings document a broad shift toward shared first-author credit across journal sizes and regions within the biomedical literature and suggest that journals and evaluators may need to rely more on transparent contributorship information and to monitor the use of such labels over time.

翻译：平等贡献作者身份（即两名或多名作者被标注为贡献相同）在科学出版中日益普遍。利用PubMed和PMC数据库（2010-2024年）中约48万条带标签记录，我们考察了平等贡献作者的时间趋势、期刊层级模式、地理分布及其在作者列表中的位置。结果显示，2017年后此类标注急剧增加，高产出巨型期刊和小型专业期刊均推动了这一增长。期刊层级分析表明，带标签文章占比的中位数从2015年的约19%上升至2024年的超过30%，部分期刊甚至超过50%。地理分布上，中国占据最大份额（占分数化贡献的40.8%），其次为美国（15.2%）和德国（5.2%）。以2015年为基线标准化后，中国至2024年增幅达13.1倍，而增长最慢的国家也提高了三倍以上。标准化作者位置分析显示，平等贡献标注集中出现在第一作者附近，中间或末位作者中较少。这些发现揭示了生物医学文献中不同期刊规模和区域的共同第一作者署名权正在发生广泛转变，并提示期刊与评审者可能需更依赖透明的贡献者信息，同时对此类标注的使用进行长期监测。