In health and medical research understanding Medical Subject Headings (MeSH) from the National Library of Medicine (US) is very helpful. In Medline and PubMed for example, articles are assessed by reviewers, who assign the appropriate term/s to them. For example the MeSH heading for premature baby is Infant, premature. Identifying other useful keywords like, pre-term, low birth weiight, NICU, premmie can be helpful.

MeSH Browser locates standardised terms for biomedical concepts, including definitions, hierarchical relationships, and scope notes for each term, making it easier to navigate complex medical topics.
MeSH on Demand reviews abstracts or research summaries giving automated relevant MeSH headings to follow via PubMed.