Menstrual blood (MB) is a common and important type of forensic evidence, especially in sexual assault cases. MB is composed of peripheral blood (PB), vaginal fluid, and endometrial cells of the uterine wall. In forensic investigations, the differentiation of MB and PB can determine whether the blood present is a result of tissue damage from an assault or a natural cause and thus help to reconstruct the event. Understanding how menstrual blood changes is necessary to develop a method for bloodstain aging. Fluorescence spectroscopy, a promising spectroscopic method for bloodstain analysis, was used to probe the biochemical changes that occur over time in menstrual bloodstains. It was found that steady-state fluorescence spectra underwent significant changes over first nine hours post deposition. The underlying mechanism of fluorescence changes was proposed to involve the kinetic transformation of three fluorophores: tryptophan, nicotinamide adenine dinucleotide and flavins.

月经血（MB）是法医证据的常见且重要类型，尤其是在性侵犯案件中。MB由子宫壁的外周血（PB），阴道液和子宫内膜细胞组成。在法医调查中，MB和PB的分化可以确定存在的血液是攻击或自然原因造成的组织损伤的结果，从而有助于重建事件。了解月经的血液变化是开发血迹老化方法所必需的。荧光光谱法是一种有前途的用于血迹分析的光谱方法，用于探测月经期血迹随时间发生的生化变化。发现在沉积后的前九小时，稳态荧光光谱发生了显着变化。