By Christian Rooney
Editor’s Note: Medical students and residents on the FACTS elective learn that the female cycle is a vital sign of health. The main event of the female cycle is not menstruation but ovulation, which is why the female cycle is best described as the ovarian-menstrual cycle. The normal cyclic ovulatory event reflects the proper functioning of internal hormones leading to external physical signs of hormonal health. Fertile cervical fluid reflects the actions of estrogen, and the progesterone-driven rise in a woman’s basal body temperature lets her know ovulation has occurred. A woman can use these cyclical signs to understand her body better and to track her fertility for family planning. Christian Rooney was on the FACTS elective when he summarized Vollmar et al’s 2024 narrative review [1] where the authors explored the female cycle as a vital sign. Dive deeper into this topic in Part D of the FACTS CME Course.
Introduction
The menstrual cycle reflects the coordinated functioning of multiple physiological systems and provides valuable insights into overall health. Some medical organizations, such as the American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics (AAP) have recognized its importance as a vital sign during adolescence.[2][3] However, in the article [1] summarized below titled, “The Menstrual Cycle as a Vital Sign: a comprehensive review,” Vollmar et al argue that menstrual cycle assessment should continue throughout adulthood and into menopause. Their review evaluates evidence showing how the female cycle meets the criteria for a vital sign; it identifies pathologies, signals wellness, and responds to internal and external exposures. By examining this data, the authors emphasize that monitoring the menstrual cycle can serve as a meaningful health indicator across a woman’s lifespan.
“The menstrual cycle reflects the coordinated functioning of multiple physiological
systems and … can serve as a meaningful health indicator across a woman’s lifespan.”
Methodology
The authors conducted a narrative review by compiling key concept terms and performing keyword and controlled vocabulary searches in the PubMed database. They targeted systematic reviews, meta-analyses, and clinical practice guidelines published since 2020. When recent literature was limited, older studies from 2010 to 2020 were included to ensure adequate coverage. The search also incorporated relevant clinical tools, established guidelines, and supplemental patient education materials to provide a broad, practical overview of the menstrual cycle’s role as a health indicator.[1]
Results
The findings demonstrate the menstrual cycle meets established criteria for a vital sign: it reflects physiological integrity, responds to internal and external changes, and can predict both current and future health outcomes. Cycle features such as length, bleeding duration, and flow intensity are influenced by hormonal, endocrine, environmental, and lifestyle factors.
“The menstrual cycle meets established criteria for a vital sign: it reflects physiological integrity, responds to internal and external changes, and can predict both current and future health outcomes.”
Physiologic parameters including heart rate, blood pressure, respiratory rate, and basal body temperature fluctuate in consistent patterns throughout the cycle, supporting its systemic relevance. Additional functions, such as metabolism, immune activity, circadian rhythm amplitude, and fluid regulation also vary cyclically.[1]
Abnormal cycle characteristics, such as irregular timing or heavy bleeding, are linked with reproductive or endocrine disorders such as polycystic ovary syndrome (PCOS), thyroid disease, hypothalamic dysfunction, and premature ovarian insufficiency.[1] [2] These irregularities may also serve as early indicators of infertility or future health issues.
Long-term associations include links between cycle irregularity or extreme cycle length and increased risk for metabolic disorders, cardiovascular disease, certain cancers, reduced bone mineral density, and even premature mortality.[1] High and low body mass index (BMI) and age were shown to influence cycle characteristics and regularity, demonstrating the cycle’s sensitivity to overall physiological balance.
Fertility awareness-based methods (FABMs) are rooted in careful observation of biological indicators such as cervical mucus, basal body temperature, and bleeding patterns. The comprehensive review by Vollmar et al [1] reinforces that these same markers provide insights beyond fertility; they reflect systemic health and can guide clinical decision-making. For FABM clinicians and educators, these findings highlight the importance of consistent cycle tracking for both fertility management and preventive health.
“For FABM clinicians and educators, these findings highlight the importance of
consistent cycle tracking for both fertility management and preventive health.”
Strengths of Vollmar et al’s review include its broad scope across adolescence through menopause, its integration of reproductive and non-reproductive outcomes, and its use of high-quality evidence when available. The inclusion of practical clinical tools and patient resources further strengthens its clinical relevance.
On the other hand, including many observational studies makes it difficult to confirm causal relationships. Some data relied on self-reported information or came from limited populations, such as women with irregular cycles or those in resource-limited settings, reducing generalizability. The quality and accuracy of tracking apps also varied, introducing possible bias. Additionally, definitions of “normal” and “irregular” cycles lack standardization across studies, making comparisons challenging.[1]
Future research should focus on prospective, longitudinal studies to establish causal links between menstrual patterns and long-term health outcomes. Improved standardization of cycle metrics and validation of app-based tracking algorithms would strengthen clinical applications and support broader integration of menstrual health monitoring into preventive medicine.
Conclusion
The review by Vollmar et al makes a strong case for recognizing the menstrual cycle as a vital sign that provides insight into a woman’s endocrine, cardiovascular, metabolic, and immune health. For the fertility awareness and FABM community, it reinforces the concept that charting the female cycle reveals more than fertility—it offers a window into overall wellness. Routine documentation of menstrual cycle characteristics across the lifespan could promote earlier detection of health concerns, enable personalized interventions, and ultimately improve outcomes in women’s health.
References
[1] Vollmar AKR, Mahalingaiah S, Jukic AM. The Menstrual Cycle as a Vital Sign: a comprehensive review. F S Rev. 2025;6(1):100081. doi:10.1016/j.xfnr.2024.100081
[2] American College of Obstetricians and Gynecologists. Menstruation in Girls and Adolescents: Using the Menstrual Cycle as a Vital Sign. Committee Opinion No. 651. Obstet Gynecol. 2015;126:e143–e146.
[3] American Academy of Pediatrics. Menstrual Health and the Adolescent: Using the Menstrual Cycle as a Vital Sign. Pediatrics. 2015;135(3):e1122–e1131.
About the Author
Christian Rooney
Christian Rooney is a fourth-year medical student at Georgetown University School of Medicine. Originally from Dallas, TX, he completed his undergraduate education at Texas A&M University. For the last three years, he has lived in Washington, DC and is currently applying for family medicine residency programs with an aim to relocate to the DFW region. After residency, Christian plans to pursue a sports medicine fellowship and envisions working in both sports medicine and primary care.
