"PubMed comprises more than 28 million citations for biomedical literature from MEDLINE, life science journals, and online books. Citations may include links to full-text content from PubMed Central and publisher web sites."
Once referred to as the "gold standard to biomedical literature," and containing numerous high quality medical research publications, it has been discovered that predatory resources have made there way into PubMed as well. This is because while PubMed does index quality resources indexed in MEDLINE, it also indexes literature from other "life sciences journals and online books."
To be safe, it is recommended to only use journals specifically stated to be "Indexed with Medline" as a precursor to publish.
To identify these journals, do the following:
1.) Go to https://www.ncbi.nlm.nih.gov/nlmcatalog/journals to see the list of journals indexed in Medline in which to publish.
2.) OR Run a search in PubMed, and then select an article title of interest. You will be taken to the article's abstract. From the article's abstract, you will see the name of the journal in which it was published. Click the journal and choose "Search in NLM Catalog."
4.) Make sure it says "Indexed in Medline." That will show that the journal is reputable.