Which other factors affect the menstrual cycle?

The menstrual cycle is affected by numerous internal and external factors, all of which can alter the cycle’s length, regularity, and symptoms. Some of these factors are not modifiable, such as race/ethnicity, age, intrauterine exposures, family history, adverse childhood events, and genetics.^[1][2] Other factors are related to the environment, like exposure to air pollution, endocrine-disrupting chemicals, and certain viruses and bacteria, as well as the geographic climate.^[1][3] There are also important personal and lifestyle factors to consider, including mental health,^[4][5], sleep health,^[6][7] body mass index,^[8][9][10] use of tobacco and cannabis,^[11][8] lactation,^[12][13] use of contraceptives (oral medications, intrauterine devices, ect.),^[14][15] shift work,^[2] and possibly even a history of concussions.^[16]

Of these factors, psychological stress is a common target for interventions aimed at restoring normal menses, reducing menstrual-related symptoms, and improving fertility. For example, acupuncture and acupressure may help some people with premenstrual syndrome or menstrual irregularity.^[17][18] Psychosocial interventions, particularly cognitive behavioral therapy and mindfulness-based therapies, may increase pregnancy rates in people with infertility^[19] and improve mood in people with premenstrual syndrome.^[20][21]