1)The menstrual cycle refers to the changes and the preparation that a women body goes through to prepare for pregnancy. 2)About once a month, the uterus grows a new lining (endometrium) to get ready for fertilized egg. 3)When there is no fertilized egg to start the pregnancy, the uterus sheds its lining starting off the monthly menstrual bleeding also called menstrual period. 4)The average cycle is 28 days, although it is perfectly normal to have a cycle in that is as short as 21 days or long as 35 days. 5)A regular menstrual cycle is an important element of successful concepton. #The four main phases of menstrual cycle are : 1- menstruation 2- the follicular phase 3-ovulation 4-the luteal phase.