The Cleveland Clinic defines a healthy menstrual cycle as between 21 and 35 days long. Lifestyle factors such as nutrition, stress levels and exercise affect hormone production, regulation of ovulation and menstrual cycle length. Irregular menstrual cycles are a reflection of abnormal hormone levels, immune system imbalances, metabolic imbalances or a combination of these factors.
Stress
Prolonged psychological stress disrupts normal menstrual cycles by increasing secretion of the hormone prolactin from the pituitary gland. Excess prolactin prevents ovulation and according to Ruth Trickey in "Women, Hormones & the Menstrual Cycle," elevated levels of prolactin are responsible for 10 to 20 percent of cases of irregular and missed periods.
Stress also causes irregular menstrual cycles by reducing the secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) from the pituitary gland. Because ovulation requires adequate levels of LH and FSH, reduced production of both hormones creates irregular menstrual cycles by disrupting ovulation. When ovulation is erratic, women experience missed periods, irregular periods, or spotting between periods.
Excessive Exercise
According to Dr. Tori Hudson, N.D. in the "Women's Encyclopedia of Natural Medicine," competitive athletes have higher incidence of irregular or absent menstrual cycles than the general population and the type, duration and intensity of exercise determine this effect.
Excessive exercise, especially when combined with low body weight and low body fat, disrupts menstrual cycles in a variety of ways. Women need between 13 and 17 percent body fat to menstruate regularly because reproductive hormones estrogen and progesterone are produced from body fat. Athletes with adequate body fat are less likely to experience irregular menstrual cycles than athletes with low body fat and low calorie diets.
Polycystic Ovarian Sundrome
Irregular menstrual cycles are common in women with polycystic ovarian syndrome (PCOS). PCOS affects four to 10 percent of women and causes irregular menstrual cycles by creating excess LH, insufficient FSH, excess testosterone, insufficient progesterone and excess prolactin. Ovarian cysts, although not always present in PCOS, sporadically interrupt ovulation and cause irregular menstrual cycles. Missed periods, irregular periods, failure to ovulate, facial hair, weight gain or trouble losing weight and episodes of low blood sugar are symptoms of PCOS.
Hypothyroidism
Hypothyroidism, or low thyroid function, causes irregular menstrual cycles by increasing prolactin hormone. When the thyroid is under-functioning, the hypothalamus gland stimulates the pituitary gland to produce thyroid stimulating hormone (TSH) and prolactin. Fatigue, depression, weight gain or trouble losing weight, poor concentration, constipation and dry skin in addition to irregular menstrual cycles are symptoms of Hypothyroidism. Causes of hypothyroidism include autoimmune disease, iodine, selenium, zinc, tyrosine and vitamin B-12 deficiencies.
References
- "Women, Hormones & the Menstrual Cycle"; Ruth Trickey; 2003
- DrWeil.com: Q&A Library
- "Medicine & Science in Sports and Exercise"; Strenuous exercise with caloric restriction: effect on luteinizing hormone secretion; Williams N et al.; 1995
- "Women's Encyclopedia of Natural Medicine"; Tori Hudson, ND; 1999
- My.ClevelandClinic.org: Normal Menstruation
