Menstruation is also called menses, menstrual period, or period. When a woman has her period, she is menstruating. The menstrual blood is consists with partly blood and tissue from the inside of the uterus (womb). It flows from the uterus through the small opening in the cervix, and passes out of the body through the vagina. This stays for 1-8 days. This process is known as menstrual cycle.

The follicle stimulating hormone (FSH) and luteinizing hormone (LH), estrogens and progesterone are the various hormones that regulate the menstrual cycle.