The uterus, or womb, is a pear-shaped sac located between the bladder and rectum. Its main purpose is to hold a fetus when you are pregnant. Every month, your body prepares the lining of the uterus to hold the fetus by building up with nutrient-rich blood, tissue and fluids. If you do not become pregnant that month, your uterus does not need this layer and sheds it, causing you to menstruate. When you have your period, you not only shed blood, but also tissue and fluids.
Some girls think that they lose a lot of blood each month.
I have really bad cramps with my period. No, this is normal. Discomfort associated with menstrual periods can range from cramps, diarrhea and frequent urination to sweating, bloating, nausea and vomiting. Mood swings, headaches and backaches and upper thigh and back pain are also common. These problems are caused by prostaglandins, hormone-like body chemicals that become more active right before your period starts.