9 - Menstruation and Menstrual Disorders: The Epidemiology of Menstruation and Menstrual Dysfunction

Abstract

This chapter focuses on the epidemiology of menstruation and menstrual disorders. Population variability in menstrual cycle length is greatest immediately after menarche and shortly before menopause, with each transition lasting approximately 2–5 years. Both transitions are characterized by an increased frequency of both very long and very short cycles and, consequently, by an increased range of cycle lengths. Menstrual disturbances are a common complaint both in industrialized and in nonindustrialized countries throughout the reproductive lifespan. Menstrual characteristics (for example, cycle length) that place a woman at increased risk of developing chronic disease may also be considered pathological. The understanding of the relationship between menstrual cycle characteristics and women's long-term risk of chronic disease remains limited. Despite the importance of menstruation in women's lives, information on the incidence and prevalence of menstrual dysfunction is scarce and the knowledge of risk factors for menstrual dysfunction is confined predominantly to studies of the impact of weight, physical activity, and stress on the risk of amenorrhea.