In light of a fair allocation of funds, it is important to better understand how authorship regulations may influence the outcomes of performance-based indicators. This study has shown in how far the authorship regulation proposed by the DFG in 2004 might have affected the author count and author position of medical publications. The DFG authorship regulation was intended to counteract the trend towards increasing author numbers in medical publications. The results indicate a general trend of increased author counts and middle authorship papers. However, the publications with the DFG authorship regulation have lower author counts and lower shares of middle-authorship papers. Even though the results may be affected by a number of other criteria, this study provides some useful, preliminary results to this issue and suggests some areas for further investigation. A fair distribution of authorship credit remains important and could suppress the tendency to unjustified inflation of co-authors because authors will be more reluctant to share their authorship with peers not truly involved in the publication. So far, bibliometric databases only include author positions and author counts. One challenge is the identification of joint first and last authorships because the byline is not included in bibliometric databases. A more complete provision of data on author contribution statements, would allow for more accurate indicators that take author position and contribution into account.