Bibliometrics analyses with Pubmed metadata I just started to have interest into bibliometric analyses, and so far I am struggling to understand the tons of copyright policies. However, these are (from my opinion) quite vague and with too much grey areas. 

Let’s say that I constrain my analyses on the metadata from Pubmed (not PMC) considering basic classes in it (i.e., title, publication year, citation number, MeSH terms, author names…);
but I never touch or analyze the abstracts (text mining or anything alike whatsoever on abstracts).


Do you think that such analyses would pass without copyright infringements?
Publication metadata does not have license restrictions. I work for the European partner of Pubmed - Europe PMC, and you can get metadata for every article available in Pubmed via the open API (https://europepmc.org/RestfulWebService). 

In some countries publication abstract may be under copyright. For UK and USA it is possible to reproduce abstracts if your use of this data falls under "fair dealing claim" (see https://www.copyrightservice.co.uk/ukcs/docs/edupack.pdf).