Following ovulation, the luteal phase sets in, which lasts roughly 10 to 14 days. This phase is named after the corpus luteum, a structure that forms from the collapsed follicle after releasing the egg. The corpus luteum produces progesterone, a hormone crucial for maintaining the uterine lining in preparation for a potential pregnancy. If fertilization occurs, the fertilized egg (now called a zygote) travels down the fallopian tube and implants itself into the uterine lining, leading to pregnancy. However, if fertilization doesn’t occur, the corpus luteum degenerates, causing progesterone levels to drop. This drop triggers the shedding of the uterine lining during the next menstrual phase, starting the cycle anew.