HCG is produced almost exclusively in the placenta. At which week of gestation HCG is maximum?
**Core Concept**
Human chorionic gonadotropin (HCG) is a hormone produced during pregnancy, primarily by the placental component of the syncytiotrophoblast. Its role is to maintain the corpus luteum, ensuring continued estrogen and progesterone production until the placenta can take over.
**Why the Correct Answer is Right**
HCG levels peak approximately 10 weeks into gestation, providing essential support to the corpus luteum until the placenta develops sufficient function to replace it. The placenta gradually starts to produce more progesterone and estrogen, reducing the need for HCG. This process allows for the continued development of the fetus.
**Why Each Wrong Option is Incorrect**
**Option A:** This is incorrect because HCG levels are typically at their highest concentration at 10 weeks, not immediately after implantation.
**Option B:** This is incorrect because HCG production is not significantly influenced by the fetal pituitary gland at this stage of gestation.
**Option C:** This is incorrect because HCG levels are not at their maximum at the end of the first trimester; they peak earlier.
**Clinical Pearl / High-Yield Fact**
HCG is a critical hormone in early pregnancy, and its levels can be used to monitor fetal development. Abnormal levels may indicate potential complications, such as ectopic pregnancy or miscarriage.
**Correct Answer: C. 10 weeks.**