Individual variation of follicular phase changes in endothelial function across two menstrual cycles.

New Findings: What is the central question of this study? The purpose of this study was to determine intra-individual reproducibility of follicular phase changes in endothelial function (flow-mediated dilatation) over two menstrual cycles in healthy, premenopausal women. What is the main finding and its importance? Phase changes in endothelial function were not consistent at the individual level across two menstrual cycles, which challenges the utility of interpreting individual responses over one cycle.

Abstract: Evidence regarding the impact of menstrual phase on endothelial function is conflicting, and studies to date have examined responses only over a single cycle.