The average menstrual cycle is 28 days and bleeding lasts for 3-5 days. However each woman's menstrual cycle is unique to her. Therefore a few less or more days in the menstrual cycle or period is common for each woman. However when the cycle changes significantly it may indicate some irregularity. Complete absence of a period (amenorrhea) for 3 or more months when the woman is not pregnant - This can be due to several causes such as excessive exercise, malnourishment, stress, obesity, thyroid or pituitary gland problems, PCOS (polycystic ovarian syndrome), hypothalamus disorders, ovarian failure, uterine disease, contraceptives and breast feeding.
These irregularities may include:
Very painful periods(dysmenorrhea) - can be caused by fibroids and endometriosis.
Very heavy periods(menorrhagia) - Can be caused by IUDs, miscarriage, ectopic pregnancy, drugs such as blood thinners and steroids, uterine fibroids, endometrial polyps, adenomyosis, blood clotting disorders and uterine cancer.
Very light periods
Periods occuring more than 35 days after the last period (oligomenorrhea) - This may be caused by PCOS, perimenopause, change in contraceptives, hormone imbalance.
Periods occuring less than 21 days after the last period (polymenorrhea) - This can be caused by pelvic inflammatory disease and endometriosis.
periods occuring at irregular intervals (metrorrhagia) - This can be due to benign cervical polyps, uterine infections, and oral contraceptives.
bleeding between menstrual periods (intermenstrual bleeding) - Can be due to hormonal contraceptives, IUDs, stress, anticoagulant drugs. It may even be an ectopic pregnancy or cancer.
In any case of menstrual irregularity, you should visit your doctor who can perform examinations and tests to determine the cause and the best course of remedy.
Many causes of menstrual problems arise from hormonal imbalance. You may want to read about natural ways to improve hormonal balance