Primary　dysmenorrhea　(PD),　as　characterized　by　painful　menstrual　cramps　without　organic　causes,　is　associated　with　central　sensitization　and　brain　function　changes.　Previous　studies　showed　the　integrated　role　of　the　default　mode　network　(DMN)　in　the　pain　connectome　and　its　key　contribution　on　how　an　individual　perceives　and　copes　with　pain　disorders.　Here,　we　aimed　to　investigate　whether　the　cingulum　bundle　connecting　hub　regions　of　the　DMN　was　disrupted　in　young　women　with　PD.　Diffusion　tensor　imaging　was　obtained　in　41　PD　patients　and　41　matched　healthy　controls　(HC)　during　their　periovulatory　phase.　The　production　of　prostaglandins　(PGs)　was　obtained　in　PD　patients　during　their　pain-free　and　pain　phases.　As　compared　with　HC,　PD　patients　had　similar　scores　of　pain　intensity,　anxiety,　and　depression　in　their　pain-free　phase.　However,　altered　white　matter　properties　mainly　located　in　the　posterior　section　of　the　cingulum　bundle　were　observed　in　PD.　Besides　PGs　being　related　to　menstrual　pain,　a　close　relationship　was　found　between　the　white　matter　properties　of　the　cingulum　bundle　during　the　pain-free　phase　and　the　severity　of　the　menstrual　pain　in　PD　patients.　Our　study　suggested　that　PD　had　trait　changes　of　white　matter　integrities　in　the　cingulum　bundle　that　persisted　beyond　the　time　of　menstruation.　We　inferred　that　altered　anatomical　connections　may　lead　to　less-flexible　communication　within　the　DMN,　and/or　between　the　DMN　and　other　pain-related　brain　networks,　which　may　result　in　the　central　susceptibility　to　develop　chronic　pain　conditions　in　PD＇s　later　life.　(C)　2017　Wiley　Periodicals,　Inc.