Question

Which of the following hormone is not secreted by human placenta ?

• A. LH
• B. hCG
• C. Estrogen
• D. Progesterone

Hint:

• Pregnancy-Specific Hormones: Hormones such as hCG, hPL, and relaxin (which is also secreted by the ovary/placenta later in pregnancy) are produced in women exclusively during gestation.

• Clinical Application: Because hCG is produced shortly after the blastocyst implants into the uterine wall, its presence in maternal urine serves as the physiological basis for home pregnancy testing.

Answer 1

The Correct Option is A

Concept:

• Endocrine Role of the Placenta: During human gestation, the placenta acts as a temporary, highly active endocrine gland. It synthesizes and secretes several hormones that are critical for maintaining the pregnancy, regulating maternal metabolism, and supporting fetal growth.

• Placental Hormones: The primary hormones produced by placental tissue (specifically the syncytiotrophoblast layer) include: itemize

• hCG (Human Chorionic Gonadotropin): Maintains the corpus luteum during early pregnancy to ensure continuous progesterone production.

• hPL (Human Placental Lactogen): Regulates maternal glucose and lipid metabolism to support fetal nutrition.

• Estrogens (primarily Estriol): Stimulate uterine growth and ductal development in the mammary glands.

• Progesterone: Maintains the stable, non-contractile state of the uterine endometrium during gestation.

Anterior Pituitary Hormones: Gonadotropic hormones, such as Luteinizing Hormone (LH) and Follicle-Stimulating Hormone (FSH), are synthesized and secreted by gonadotroph cells in the anterior pituitary gland under the regulation of hypothalamic GnRH. itemize

Step 1: Analyze the biological source of the listed hormones
During pregnancy, the levels of estrogen and progesterone rise significantly. These hormones are synthesized directly by the placenta to support the growing fetus. Similarly, hCG is produced by the developing chorion/placenta shortly after implantation.

Step 2: Identify the hormone of non-placental origin
Luteinizing Hormone (LH) is a pituitary gonadotropin. During pregnancy, the extremely high levels of circulating placental estrogen and progesterone exert a strong negative feedback effect on the maternal hypothalamus and anterior pituitary gland. This feedback mechanism suppresses the secretion of LH and FSH to prevent the maturation of new ovarian follicles. Consequently, LH is not secreted by the placenta. This corresponds to option (A).