The luteal phase is the second half of the menstrual cycle that starts right after ovulation (when an egg is released from the ovary) and lasts until the first day of the next menstrual period. It typically begins around day 15 of a 28-day cycle and lasts about 12 to 14 days, although it can range from 9 to 17 days in a normal cycle. During this phase, the corpus luteum (formed from the follicle that released the egg) produces progesterone to thicken the uterine lining in preparation for a potential pregnancy. If fertilization does not occur, hormone levels drop, leading to the start of menstruation and the end of the luteal phase.
So, the luteal phase usually spans from about day 15 to day 28 of a typical menstrual cycle but may vary depending on individual cycle length and when ovulation occurs.
