What factors influence irregular menstrual cycles (menses)?

From the Guidelines

Irregular menstrual cycles can be influenced by numerous factors, including hormonal imbalances, stress, significant weight changes, excessive exercise, polycystic ovary syndrome (PCOS), thyroid disorders, and certain medications, with PCOS being a common cause of irregular periods in women, affecting approximately 4–6% of women in the general population 1. The factors that influence irregular menstrual cycles can be broadly categorized into:

• Hormonal imbalances, such as those caused by polycystic ovary syndrome (PCOS) or thyroid disorders
• Lifestyle factors, including stress, significant weight changes, and excessive exercise
• Medical conditions, such as endometriosis, uterine fibroids, pelvic inflammatory disease, and diabetes
• Certain medications, including antipsychotics, antidepressants, chemotherapy drugs, and corticosteroids
• Age-related transitions, such as puberty and perimenopause
• Pregnancy, which is another obvious cause of missed periods It is essential to note that the prevalence of PCOS in patients with temporal lobe epilepsy has been found to be between 10% and 25% even if they were not receiving antiepileptic drugs 1. According to a recent study, functional hypothalamic amenorrhoea (FHA) is another common cause of irregular menstrual cycles, affecting about 3–4% of women in the general population, and is characterized by chronic anovulation, which is not due to identifiable organic causes 1. The diagnosis of irregular menstrual cycles involves a comprehensive evaluation, including medical history, physical examination, and laboratory tests, such as measurement of serum levels of luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, progesterone, testosterone, and androstenedione 1. Treatment options for irregular menstrual cycles depend on the underlying cause and may include hormonal medications, lifestyle modifications, or specific treatments for underlying conditions, such as combined oral contraceptives starting with low-dose formulations, or surgery, including endometrial ablation and hysterectomy, if medical treatment fails or is contraindicated 1.

From the FDA Drug Label

When you do not produce enough progesterone, menstrual irregularities can occur. Progesterone capsules are used for the treatment of secondary amenorrhea (absence of menstrual periods in women who have previously had a menstrual period) due to a decrease in progesterone

The factors that influence irregular menstrual cycles (menses) include:

• Decrease in progesterone production: A decrease in progesterone production can lead to menstrual irregularities, as stated in the progesterone capsules label 2.
• Hormonal imbalance: The use of estrogen-containing medications without a progestin can increase the chance of developing endometrial hyperplasia, suggesting that hormonal balance plays a role in menstrual regularity 2.
• Ovulation inhibition: Inhibition of ovulation, as seen with oral contraceptives, can lead to increased menstrual cycle regularity, decreased blood loss, and decreased incidence of dysmenorrhea 3.

From the Research

Factors Influencing Irregular Menstrual Cycles

The following factors have been identified as influencing irregular menstrual cycles:

• Hormonal changes: Irregular periods can occur due to changes in the body's levels of estrogen and progesterone hormones, which disrupt the normal pattern of the period 4
• Medical conditions: Menstrual irregularity has been found to be associated with various diseases and medical conditions, such as metabolic syndrome, coronary heart disease, type 2 diabetes mellitus, and rheumatoid arthritis 4
• Polycystic ovary syndrome (PCOS): PCOS, characterized by irregular menstrual cycles and hyperandrogenism, is a common ovulatory disorder 5
• Stress: Chronic stress has been detected as a risk factor for irregular menstrual cycles 6, 7
• Lifestyle factors: Factors such as smoking, body mass index, physical activity, and occupational factors (e.g. prolonged standing, frequent heavy lifting, rotating night shift) have been associated with irregular menstrual cycles 5, 7, 8
• Age and age at menarche: Menstrual cycle irregularity has been found to decrease with age and increase with age at menarche 7, 8
• Parity: Parous women have been found to have a lower tendency of irregular cycles 8
• Psychological factors: Dispositional resilience has been found to be a protective psychological trait that modulates reproductive functioning, and women with greater dispositional resilience have reduced risk for irregular menstrual cycles in the face of low to moderate chronic stress 6

Associated Health Problems

Irregular menstrual cycles have been associated with various health problems, including:

• Anemia, osteoporosis, psychological problems, impaired quality of life, and infertility 4
• Cardiometabolic conditions, such as obesity, prediabetes, type 1 and 2 diabetes, high cholesterol, hypertension, metabolic syndrome, arrhythmia, congestive heart failure, coronary artery disease, heart attack, heart valve disease, stroke, transient ischemic attack (TIA), deep vein thrombosis, and pulmonary embolism 5
• Menstrual distress, depressive symptoms, stress, fatigue, anxiety, and sleep problems 8