A: volcano map in positive ion mode, B: volcano map in negative ion mode, C: KEGG pathway enrichment map in positive ion mode, D: KEGG pathway enrichment map in negative ion mode. In the volcano map, the x-axis represents the difference multiple, the y-axis represents the P-value, and the scatter size represents the VIP value. Blue dots indicate down-regulation, red dots indicate up-regulation, and gray dots indicate no significant difference. In the KEGG pathway enrichment map, the x-axis is the ratio of the number of differential metabolites to the total number of metabolites, and the y-axis is the name of the pathway. The larger the point, the more the number of metabolites enriched, and the redder the color of the point, the more significant the enrichment pathway. KEGG: Kyoto Encyclopedia of Genes and Genomes; POI: premature ovarian insufficiency.