Menstruation is the most visible phase of the menstrual cycle and its beginning is used as the marker between cycles. The first day of menstrual bleeding is the date used for the last menstrual period (LMP). There are many physical and emotional changes that can signal that your period is on the way, including tender breasts, mood changes, and tiredness. While we all experience symptoms differently, most women start to notice these symptoms between one and two weeks before they get their period [1]. Your menstrual cycle begins on the first day of your period. Your cycle prepares your body for a possible pregnancy. The average cycle lasts between 24 and 38 days. Symptoms before your period range from fatigue and bloating to breast pain and cramping. Here, find signs that may mean your period is coming. What is a normal menstrual cycle? Your period — and the PMS symptoms that can accompany it — is just one part of your monthly menstrual cycle. Menstruation — aka having your period — is when blood and tissue from your uterus comes out of your vagina. It usually happens once every month. As your period gets lighter, one pair can take you through the day and night (just like regular underwear). But again, everybody Periods differently, so you need to take one cycle to figure out exactly how often you need to change. Understand how to track your menstrual cycle and what to do about irregularities. Do you know when your last menstrual period began or how long it lasted? If not, it might be time to start paying attention. When you track your menstrual cycles, you learn what's typical for you. Triggered by falling progesterone levels, menstruation (commonly referred to as a period ) is the cyclical shedding of the lining, and is a sign that pregnancy has not occurred. Each cycle occurs in phases based on events either in the ovary (ovarian cycle) or in the uterus (uterine cycle). Menstruation (or period) happens monthly. As the uterus sheds its lining, vaginal bleeding follows. Menstrual blood is made of blood and tissue.