The normal length of a woman's menstrual cycle is 28 days, although this varies between individuals. Irregular menstruation is when the length of the cycle is more than 35 days, or if the duration varies.
A period, or menstruation, is the part of the menstrual cycle in which the endometrium, which is the lining of the uterus, is shed. This appears as bleeding from the womb that is released through the vagina.
Irregular periods, also called oligomenorrhea, can occur if there is a change in contraception method, a hormone imbalance, hormonal changes around the time of the menopause, and endurance exercises.
Treatment for irregular periods during puberty and around the menopause is not usually necessary, but if irregular periods occur during the reproductive years, medical advice may be necessary.
Contents of this article:
Regular and irregular periods
In regular menstruation, a woman's cycle follows a predictable pattern.
A menstrual cycle lasts around 28 days, but it can vary from 24 days to 35 days, depending on the individual. Most women have between 11 and 13 menstrual periods each year.
Menstrual bleeding usually lasts for about 5 days, but this too can vary, from 2 to 7 days.
When menstruation first starts, it can take up to 2 years to establish a regular cycle. After puberty, most women's menstruation is regular. The length of time between each period is similar.
However, for some women, the time between periods and the amount of blood shed vary considerably. This is known as irregular menstruation.
Changes associated with irregular periods
A number of factors increase the chance of irregular menstruation, mostly related to hormone production. The two hormones with an impact on menstruation are estrogen and progesterone. These are the hormones that regulate the cycle.
Life cycle changes that influence the hormonal balance include puberty, menopause, pregnancy, and childbirth, and breastfeeding.
During puberty, the body undergoes major changes. It can take several years for the estrogen and progesterone to reach a balance, and irregular periods are common at this time.
Before the menopause, women often have irregular periods, and the amount of blood shed may vary. Menopause occurs when 12 months have passed since the woman's last menstrual period. After the menopause, a woman will no longer have periods.
During pregnancy, menstruation ceases, and most women do not have periods while they are breast-feeding.
Contraceptives can cause irregular bleeding. An intrauterine device (IUD) may cause heavy bleeding, while the contraceptive pill can cause spotting between periods.
When a woman first uses the contraceptive pill, she may experience small bleeds that are generally shorter and lighter than normal periods. These usually go away after a few months.
Other changes that are associated with irregular periods include:
- Extreme weight loss
- Extreme weight gain
- Emotional stress
- Eating disorders, such as anorexia or bulimia
- Endurance exercise, for example, marathon running.
There are also a number of disorders that are linked with missed or irregular menstruation.
Diseases and conditions that affect menstruation
Polycystic ovarian syndrome (PCOS) is a condition in which a number of small, fluid-filled sacs known as cysts develop in the ovaries.
Women with PCOS have unusually high levels of the male sex hormone, androgen, or testosterone.
According to the Office on Women's Health at the United States Department of Health and Human Services, PCOS affects between 10 percent and 20 women of reproductive age, or up to 5 million American women. Girls as young as 11 years old have been diagnosed with PCOS.
Cancer of the uterus or the cervix can cause unusual bleeding.
A thyroid disorder can cause irregular periods. The thyroid gland produces hormones that affect the body's metabolism.
Endometriosis is a condition in which cells that are normally found inside the uterus, called endometrial cells, grow outside it. In other words, the lining of the inside of the uterus is found outside of it.
Endometrial cells are the cells that shed every month during menstruation, so endometriosis is most likely to affect women during their childbearing years.
The cellular growth involved in endometriosis is not cancerous. There may be no symptoms, but it can be painful, and it can lead to other problems. If released blood gets stuck in surrounding tissue, it can damage the tissue, causing severe pain, irregular periods, and infertility.
Pelvic inflammatory disease (PID) is an infection of the female reproductive system. Among women, it is the most common and serious complication of sexually transmitted infections (STIs), apart from AIDS.
If detected early it can be treated with antibiotics, but if it spreads, it can damage the fallopian tubes and the uterus, resulting in chronic, or long-term, pain. There are many symptoms, and they including bleeding between periods and after sex.
Treatment options for irregular periods
If the irregular periods occur during puberty or as the woman approaches the menopause, treatment is not usually necessary.
If irregular bleeding is due to contraception and continues for months, the woman should talk to a health care professional about alternative contraception options.
If a woman has PCOS, is overweight or obese and also has irregular periods, losing weight may help.
A lower weight means the body does not need to produce so much insulin. This leads to lower testosterone levels and a better chance of ovulating.
A low-dose birth control pill that containing a combination of estrogen and progesterone may help. This will decrease androgen production and will help to correct abnormal bleeding.
Alternatively, taking progesterone for 10 to 14 days each month is likely to regulate the periods.
If thyroid problems cause irregular bleeding, treatment for the underlying problem is likely to be prescribed. This may include medication, radioactive iodine therapy or surgery.
Psychological therapy may help if emotional stress, an eating disorder or sudden weight loss have caused irregular periods. This may include relaxation techniques, stress management, and talking to a therapist.