Where Am I? Four Stages in Your Menstrual Cycle. The following is a break down of the four phases of a menstrual cycle. Phase One— Menstruation— "Having Your Period" What’s happening: Your body is getting rid of tissue it doesn’t need. More information: When you menstruate, the lining of the uterus, (the endometrium), breaks up and passes slowly from the uterus through the vagina to the outside of your body. This menstrual "flow" drips out slowly. It can look like a lot of blood, but it’s actually a mixture of blood, mucus, and body cells, amounting to a total of about 6-9 tablespoons, on average, for each period—with only about three of those tablespoons being blood. The flow might be red or quite dark, and might include some clumps or clots. Phase Two— Pre-Ovulation Phase (right after your period ends) What’s happening: Your body is preparing an egg for pregnancy. More information: About the time your flow stops, your ovaries start to prepare another egg, or ovum, for release into one of the fallopian tubes (usually, the ovaries take turns releasing eggs—the left ovary one month, the right ovary the next month). At the same time, a hormone called estrogen tells your uterus to build up the endometrium. Phase Three— Ovulation What’s happening: A lot happens in this phase, but basically the egg is released from the ovary into the fallopian tubes, and your body is preparing the uterus to receive a fertilized egg (if there is one). More information: As Phase Two ends, your brain sends a new hormonal signal to your ovaries, telling one ovary to release the mature egg (ovum). This step is called ovulation. First, the egg moves through the fallopian tube toward the uterus. At the same time, the endometrium is growing even thicker because of the hormone progesterone. This happens so the body is ready in case the egg is fertilized. If the egg isn’t fertilized, your body knows that it doesn’t need its "nest" any longer. Although phases of the menstrual cycle can vary in length, the number of days between ovulation and the menstrual period is consistent—ovulation usually occurs 14 days before the start of your next period. Phase Four— The Premenstrual (Luteal) Phase What’s happening: if a woman has not become pregnant, the uterus gets ready to release the unneeded tissue that was prepared for the egg. More information: Levels of two hormones involved in the development of the uterine lining, estrogen and progesterone, begin to drop. The stimulation for the endometrium is lost. This causes the shedding of the lining to begin, and a new menstrual cycle starts. Use the period predictor to learn more about your individual cycle: Learn about the menstrual cycle and get helpful information and tips at BeingGirl.com.