(Days 1-5, approximately): This is when the uterine lining, built up during the previous cycle, is shed as menstrual bleeding. This marks the first day of the cycle.

(Days 1-14, approximately): This is the phase that corresponds with menstruation. Hormones encourage the growth of follicles in the ovaries, each containing an egg. typically, one egg becomes dominant and matures. This is a time of rising estrogen levels, which causes the lining of the uterus to thicken once again. 

(Day 14): A surge in luteinizing hormone (LH) triggers the release of the mature egg from the ovary. This is called ovulation. The egg travels down the fallopian tube, where it can be fertilized by sperm. 

(Days 14-28, approximately): After ovulation, the empty follicle becomes the corpus luteum, which produces progesterone and estrogen. These hormones maintain the thickened uterine lining, thus preparing it for the possible implantation of a fertilized egg. If no egg is fertilized, the corpus luteum degenerates, hormone levels fall, and the cycle starts again with menstruation.