If fertilization does not occur, the corpus luteum regresses, and progesterone levels will do what?

If fertilization does not occur, the corpus luteum regresses, and progesterone levels will do what?

• A. Increase
• B. Decrease
• C. Stay the same
• D. Fluctuate

Answer: (B)

Progesterone is produced by the corpus luteum after ovulation to prepare and maintain the uterine lining for possible implantation. If fertilization does not occur, there is no embryo to secrete hCG to rescue the corpus luteum, so it regresses (luteolysis). As the corpus luteum breaks down, progesterone production falls, removing endometrial support and leading to menstruation. So, progesterone levels decrease. An increase would occur only if pregnancy were established and hCG maintained the corpus luteum; staying the same or fluctuating do not describe the luteolysis situation.

Progesterone is produced by the corpus luteum after ovulation to prepare and maintain the uterine lining for possible implantation. If fertilization does not occur, there is no embryo to secrete hCG to rescue the corpus luteum, so it regresses (luteolysis). As the corpus luteum breaks down, progesterone production falls, removing endometrial support and leading to menstruation. So, progesterone levels decrease. An increase would occur only if pregnancy were established and hCG maintained the corpus luteum; staying the same or fluctuating do not describe the luteolysis situation.