The menstrual cycle as a vital sign: a comprehensive review

Some medical professional organizations have advocated for including the menstrual cycle as a vital sign in adolescence but not in adulthood. However, documenting menstrual cycle patterns is not routine clinical or research practice. Vital signs are used to predict health outcomes, indicate needed treatment, and monitor a clinical course. They can help identify pathologies, affirm wellness, and are responsive to exposures. Here, we review the scientific evidence showing how the menstrual cycle meets these criteria and should, therefore, be treated as a vital sign. Using key words and controlled vocabulary terms, we performed multiple literature searches, prioritizing the inclusion of systematic reviews, meta-analyses, and clinical practice guidelines. This review describes how the menstrual cycle is a health indicator, how it cyclically can impact health conditions, and its associations with long-term postmenopausal health outcomes. We review exposures influencing the menstrual cycle, evidence underlying its use to optimize wellness, and available tools for documenting cycles. Supplemental materials include patient handouts on menstrual cycle tracking and an index of related clinical practice guidelines and reviews by subject. The menstrual cycle is a vital sign from menarche through menopause, an underused but powerful tool for understanding gynecological and general health.