Irregular periods

Periods start at puberty and continue until the menopause. The average menstrual cycle lasts 28 days, but periods may occur as often as every 24 days or as infrequently as every 35 days. After puberty, most women develop a regular menstrual cycle with a relatively consistent length of time between periods. In some women, however, periods remain irregular. Menstrual bleeding normally lasts between 2 and 7 days, with the average length of bleeding being 5 days.



What are the causes?

Variations in the length of the menstrual cycle are usually the result of a temporary hormonal imbalance. Fluctuations in hormone levels during puberty mean that periods are often irregular when they first start, and wide variations in a woman’s normal pattern of bleeding are common in the first few months following childbirth and with the approach of the menopause.

Hormonal imbalances at other times may be caused by factors such as stress, depression, and severe or long-term illness. Excessive exercise and extreme loss of weight are also common causes of hormonal disturbance that can cause menstruation to become irregular.

Occasionally, irregular menstruation may be a symptom of a disorder of the ovaries or of the uterus. For example, polycystic ovary syndrome, in which there is an imbalance of the sex hormones, or endometriosis, in which fragments of the tissue that normally lines the uterus are displaced and become attached to other organs in the pelvis, may disrupt periods.

In some cases, an unsuspected pregnancy produces irregular bleeding that could easily be mistaken for a period. A single, late, heavy period may be due to a miscarriage. If you have a late period that is accompanied by severe abdominal pain, you should seek medical attention urgently because it may be due to an ectopic pregnancy. In some cases, the cause of irregular menstruation is unknown.

What might be done?

Irregular periods due to the normal hormonal changes that follow puberty or childbirth usually become more regular with time. In women who are approaching the menopause, irregular periods will eventually cease altogether. In all these cases, treatment is not usually necessary. However, if the problem persists and interferes with a woman’s lifestyle, drugs may be given to regulate menstruation. These drugs include oral contraceptives for younger women and hormone replacement therapy for women near menopause. Irregular menstruation that is due to extreme weight loss, excessive exercise, stress, or depression should become more regular once these problems have been overcome.

If there is no obvious cause for your irregular periods and no apparent pattern to menstrual bleeding, your doctor may arrange for you to have tests to look for underlying disorder. These may include a pregnancy test, blood tests to measure hormone levels, and ultrasound scanning of the pelvic region to look at the ovaries and uterus. If an underlying disorder is discovered, treatment of that disorder should regulate periods in most cases.