Fig. 8

A High-frequency keyword co-occurrence network with more than 5 occurrences obtained using VOSviewer. Each node represents a keyword, with node size proportional to its occurrence frequency. Lines indicate co-occurrence relationships. Keywords such as "preeclampsia," "hypertension," and "oxidative stress" dominate the network, highlighting major research focuses. B High-frequency keyword co-occurrence network with more than 100 occurrences obtained using CiteSpace. Each node represents a keyword, with node size proportional to its occurrence frequency. Lines show co-occurrence relationships, with "preeclampsia," "pregnancy," and "endothelial dysfunction" as central themes, reflecting core areas of study in preeclampsia research