Which hormone is secreted by the placenta and used for the early determination of pregnancy?

• A. Follicle stimulating hormone
• B. Human chorionic gonadotropin (HCG)
• C. Luteinizing hormone
• D. Progesterone

Answer: (B)

The hormone that signals pregnancy first and is used in early pregnancy testing is produced by the placenta after implantation. This hormone, detectable in both blood and urine, is the basis for most pregnancy tests because it appears early in pregnancy as the placental tissue forms and starts functioning. It also helps sustain the pregnancy by rescuing the corpus luteum, which continues to secrete progesterone to maintain the uterine lining until the placenta takes over that role later on.

The other hormones listed aren’t produced by the placenta. Follicle-stimulating hormone and luteinizing hormone come from the pituitary gland and regulate the menstrual cycle rather than indicating pregnancy. Progesterone is produced by the corpus luteum (and later by the placenta), but it isn’t a specific early marker for pregnancy and can be influenced by various factors, so it isn’t used for early detection in the way hCG is.