Menstrual disorders consist of changes in the normal menstruation process.
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Menstruation, also called menses, is just one part of the menstrual cycle in which your body prepares for pregnancy each month. A menstrual cycle is counted from the first day of one period (the first day of bleeding) to the first day of the next period. An average cycle is 28 days, but anywhere from 21-35 days is normal.
At the beginning of your cycle, the hormones estrogen and progesterone are at very low levels. During menstruation, levels of estrogen, which is made by your ovaries, start to rise and make the lining of your uterus grow and thicken. In the meantime, an egg (ovum) in one of your ovaries starts to mature. It is encased in a sac called the Graafian follicle, which continues to produce estrogen as the egg grows.
At about day 14 of a typical 28-day cycle, the sac bursts and the egg leaves your ovary, and the egg remains near the entrance to the fallopian tube until fertilized by a male sperm, after which it begins traveling through one of the fallopian tubes to the uterus. The release of the egg from the ovary is called ovulation.
After the egg is expelled, the follicle sac (now called a corpus luteum) remains in the ovary, where it continues producing hormones, but now mainly progesterone. The rising levels of both estrogen and progesterone help build up the uterine lining to prepare for pregnancy.
The few days before, during, and after ovulation is your "fertile period"—the time when you can become pregnant. Because the length of menstrual cycles varies, you may ovulate earlier or later than day 14. It's even possible for you to ovulate while you still have your period if that month's cycle is very short or period is very long. (Stress and other things can sometimes cause a cycle to be shorter or longer.) Regardless of what day in the cycle ovulation occurs, the corpus luteum will continue producing hormones only for 14 days, unless the egg is fertilized. Sperm from a man fertilizes the egg.
The fertilized egg becomes an embryo, passes down the fallopian tube, and implants in the lining of the uterus. The growing pregnancy releases a hormone (hCG), which stimulates the corpus luteum. The corpus luteum makes all the progesterone needed to keep the egg implanted and growing until a placenta (an organ connecting the fetus to the mother) develops. The placenta then makes hormones and provides nourishment from the mother to the growing embryo.
If an egg is not fertilized, the corpus luteum stops making hormones (in 14 days) and gets reabsorbed in the ovary. Estrogen and progesterone levels drop again, the lining of the uterus breaks down, menstruation (bleeding) begins, and the cycle starts all over again.
This cycle will continue every month starting from about age 12 years old to an average age of 51 years old when menopause signals the end of menses and the ability to become pregnant.
Most women lose an average of about 2 ounces (60 milliliters [mL]) of blood or less during normal menstruation. However, in some women, menstrual bleeding can be significantly heavier and/or longer. This is called menorrhagia. This happens if you lose more than 80 mL of blood and have a period lasting for more than seven days. This can be caused by a number of conditions and can lead to anemia and other complications.
The absence of menstruation is categorized as primary or secondary. Primary amenorrhea occurs when a girl does not start to menstruate within the normal time frame of sexual development. Primary amenorrhea is diagnosed if there is no menses by age 14 in the absence of growth or development of secondary sexual characteristics; or if there is no menses by age 16 regardless of presence of normal growth and development with the appearance of secondary sexual characteristics.
Secondary amenorrhea occurs when previously initiated menstrual periods are absent for at least three cycles (for reasons other than menopause).
Amenorrhea can be caused by:
Due to the underlying low estrogen, prolonged amenorrhea can lead to a decrease in bone density and an increased risk of osteoporosis.
In addition to menorrhagia and amenorrhea, other types of abnormal bleeding may occur, such as:
Less commonly, women may ovulate, but changes in the length of the follicular phase or other conditions can cause:
There are many causes of abnormal bleeding. Examples of causes include:
This in-depth report focuses on menorrhagia and amenorrhea.
Amenorrhea. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated January 21, 2011. Accessed August 20, 2012.
Heavy menstrual bleeding. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated 25, 2012. Accessed August 20, 2012.
Menstruation and the menstrual cycle fact sheet. Womens Health.gov website. Available at: http://www.womenshealth.gov/publications/our-publications/fact-sheet/menstruation.cfm. Updated October 21, 2009. Accessed August 20, 2012.
Last reviewed September 2014 by Andrea Chisholm, MDLast Updated: 9/17/2014