The Menstrual Cycle

• The menstrual cycle is the process during which your body prepares for pregnancy. Hormone changes during the cycle trigger the ovaries to release an egg.
• The eggs are contained within fluid-filled cavities called follicles. Both ovaries have many follicles, each containing an egg. During the first part of the menstrual cycle, one of the follicles prepares to release an egg. The follicle produces increasing amounts of estrogen, which causes the lining of the uterus to thicken and the cervix to produce "fertile mucus". This "fertile mucus" is important. A high estrogen level triggers the surge of another hormone Luteinizing hormone (LH). Ovulation normally occurs 24 to 36 hours after the LH surge, when the follicle ruptures, releasing an egg.
• The egg can be fertilized for up to 24 hours after ovulation. If fertilization does not occur, estrogen levels will gradually fall. The lining of the womb is shed and the menstrual flow begins, marking the start of the next cycle.