Figure 3. Keyword co-occurrence network in immunotherapy research for RPL. This VOSviewer-generated network visualizes the co-occurrence of keywords in the analyzed literature on immunotherapies for RPL. Keywords are grouped into thematic clusters based on their frequency and co-appearance in publications, with colors denoting distinct research themes: red cluster (focused on thrombophilia, antiphospholipid antibodies, anticoagulant therapies [e.g., aspirin and enoxaparin], and pregnancy complications); green cluster (includes terms related to immunotherapeutic strategies such as natural killer [NK] cells, cytokines, and in vitro fertilization [IVF]); yellow cluster (pertains to paternal cell immunization, progesterone, and IVF failure); blue cluster (covers immune response elements such as tumor necrosis factor, vitamin D, and immunogenetic polymorphisms); and purple cluster (represents emerging or less commonly studied concepts in immunogenetics and immunological susceptibility to pregnancy loss). Node size indicates keyword frequency, while edge thickness denotes the strength of co-occurrence. Central nodes represent broader, widely discussed topics, whereas peripheral nodes reflect niche areas of research.