The ovaries are located on the sides of the uterus, near the fallopian tubes. A normal cycle can be shorter or longer than this, though, and may range from 23-35 days. If an egg is not fertilized, it moves from the tube to the uterus and eventually is absorbed or disintegrates. Estrogen and progesterone levels decrease, and the lining of the uterus is shed as menstrual fluid on about day 28. The beginning of a menstrual period marks the start of a new cycle.
Menstrual fluid is made up of blood and tissue lining the uterus.
Sometimes you may see blood clots.