alleryAt about which stage of pregnancy does the placenta take over progesterone production from the corpus luteum?
- 3 weeks
- 12 weeks
- 6 weeks
- 24 weeks
Show answer and solution
Correct answer: B. 12 weeks
1. Early pregnancy depends entirely on the corpus luteum for progesterone.
2. The placenta develops over the first months and gradually gains endocrine function.
3. By about 12 weeks the placenta produces enough progesterone to sustain the pregnancy alone.
4. From that point the corpus luteum regresses without ending the pregnancy.
5. This is exactly why ovary removal is dangerous before 12 weeks but far less so after.
_Source: NECTA ACSEE 2023 Biology 133/1, Question 5: Reproduction_