Which of the following hormones is NOT produced by the placenta at any point during pregnancy?

• A. Human chorionic gonadotropin.
• B. Relaxin.
• C. Melatonin.
• D. Estrogen.

Answer: (C)

Verified step by step guidance

1. Understand the role of the placenta in hormone production during pregnancy. The placenta is an organ that develops in the uterus during pregnancy and is responsible for producing several hormones that support pregnancy.
2. Identify the hormones that are typically produced by the placenta. These include human chorionic gonadotropin (hCG), relaxin, estrogen, and progesterone.
3. Recognize that melatonin is a hormone primarily produced by the pineal gland in the brain, not the placenta. It regulates sleep-wake cycles and is not involved in pregnancy maintenance.
4. Compare the list of hormones provided in the question with the known hormones produced by the placenta. Human chorionic gonadotropin, relaxin, and estrogen are all produced by the placenta.
5. Conclude that melatonin is the hormone not produced by the placenta during pregnancy, as it is not involved in the functions typically supported by placental hormones.