What is the typical duration of the luteal phase?

• A. 7 days
• B. 10 days
• C. 14 days
• D. 21 days

Answer: (C)

The luteal phase is the second half of the menstrual cycle, after ovulation, when the corpus luteum produces progesterone to prepare the endometrium for possible implantation. It typically lasts about 14 days, which is relatively constant regardless of the overall cycle length. In a typical 28-day cycle, ovulation happens around day 14, so the luteal phase runs from about day 14 to day 28, roughly 14 days. If pregnancy occurs, hCG from the embryo maintains the corpus luteum, but the length of the luteal phase itself remains around 14 days.

That’s why 14 days is the best answer. The other durations are shorter or longer than the usual two-week luteal phase and don’t align with the standard length governed by the corpus luteum’s lifespan.