What physiological change occurs during the luteal phase if fertilization does not happen?

• A. Endometrial thickening
• B. Menstrual bleeding
• C. Follicle maturation
• D. Ovulation

Answer: (B)

During the luteal phase of the menstrual cycle, if fertilization does not occur, the correct physiological change is menstrual bleeding. This phase follows ovulation and is characterized by the presence of the corpus luteum, which secretes hormones such as progesterone.

If no fertilization occurs, the corpus luteum degenerates, leading to a drop in hormone levels, particularly progesterone. This hormonal decrease triggers the shedding of the endometrial lining through a process known as menstruation. Menstrual bleeding signals the beginning of a new cycle as the body prepares to discard the thickened uterine lining that was prepared to support a potential pregnancy.

In contrast, endometrial thickening occurs during the follicular phase leading up to ovulation, follicle maturation is a process that occurs within the ovarian cycle prior to ovulation, and ovulation itself is the process of releasing an egg from the ovary, which, in the absence of fertilization, does not lead to the luteal phase maintaining its function. Thus, when fertilization does not occur, the direct outcome of hormonal changes during the luteal phase is menstrual bleeding.