Women in their reproductive years experience periodic vaginal discharge of blood, otherwise known as menstrual bleeding. Also termed menstruation, menses or period, this physiologic bleeding is caused by the shedding of the lining of the uterus brought about by hormonal changes. At times, women observe a gooey tissue mixing with the blood discharges during menstruation. The fleshy substance that accompanies menstrual bleeding is actually the endometrial or uterine lining that has been cast off.

The volume of menstruation differs among women but, normally, the amount of blood loss would range from 2 to 5 tablespoons or 30 to 75 milliliters. Existing lifestyle, level of physical activity and exercise may also affect the quantity of menstrual bleeding. The blood discharges during the first two days of menstruation is usually dark red and slowly becomes brown towards the end of the duration. Slow or light bleeding produces blood that is also brownish in color. The menstrual cycle ranges from 21 to 35 days, averaging 28 days and begins on the first day of the menstruation. Duration of the period, which starts with a heavier blood flow that gradually decreases on the succeeding days, lasts within a week from about three to seven days.


Hormones secreted by the glands of the body’s endocrine system are responsible for the menstrual bleeding that women experience monthly. Specifically, these hormones affecting menstrual bleeding are the gonadotrophin-releasing hormone (GnRh) produced in the hypothalamic area of the brain, the follicle stimulating hormone (FSH) and luteinizing hormone (LH), which are released by the brain’s pituitary gland and the hormones estrogen and progesterone from the ovaries.

The cycle of menstruation starts with the hypothalamus secreting the gonadotrophin-releasing hormone (GnRh), which moves towards the pituitary gland signaling it to produce the follicle-stimulating hormone (FSH). The follicle-stimulating hormone (FSH) finds its way to the ovaries to help in the growth of the ovarian follicles, where the eggs mature and to induce estrogen secretion. As estrogen level rises, the uterine lining starts to thicken and the pituitary gland secretes the luteinizing hormone (LH). The mature egg is then released from the ovarian follicle; and progesterone is produced as the follicle collapses. If fertilization does not occur or when sperm does not unite with the egg, estrogen and progesterone levels drop eventually leading to the shedding of the uterine walls and menstrual bleeding.


There are some cases when women experience menstrual cramps with menstruation bleeding. As the walls of the uterus shed off during menstruation, a chemical known as prostaglandin, which stimulates spasmodic contractions of the uterine muscles and the surrounding abdominal walls, is released at an elevated level. The contractions forcefully expel the menstrual bleeding fluids, primarily composed of blood and small amounts of clots, old uterine linings and cervical tissues. Menstruation associated with menstrual cramps is referred to as dysmenorrhea.

Light menstruation is bleeding that occurs infrequently and at a longer interval. Termed as oligomenorrhea, this condition is also characterized by light bleeding and is often experienced by women in the menopause stage. This type of scanty menstruation is also called hypomenorrhea. Another kind of abnormal menstrual bleeding is polymenorrhea or very frequent menstrual periods. Menstrual bleeding takes place at a very close interval, having a cycle of less than 21 days. Menorrhagia occurs when there is excessive menstrual bleeding with a longer duration but at a regular interval. Dysmenorrhea may sometimes appear with this abnormal menstrual bleeding condition. Spotting between menstrual periods is known as metrorrhagia and may be brought about by normal physiologic ovulation. Amenorrhea, on the other hand, is the absence of a menstrual period frequently evident among pregnant and lactating mothers.

The menstrual cycle is a periodic process brought about by the interplay of hormones resulting to menstruation. The duration, volume and quality of vaginal blood flow, interval and frequency of menstrual bleeding indicate wellness or abnormalities that require medical attention.