Which of the following hormone promotes the development of fibroids ?
**Core Concept**
Estrogen plays a crucial role in the growth and development of uterine fibroids, which are benign tumors that arise from the smooth muscle layer of the uterus. The balance between estrogen and progesterone levels influences the growth and regression of fibroids.
**Why the Correct Answer is Right**
Estrogen promotes the growth of fibroids by stimulating the proliferation of smooth muscle cells and the deposition of extracellular matrix. This results in the enlargement of the fibroid. Estrogen receptors are present in the smooth muscle cells of the uterus, and the binding of estrogen to these receptors triggers a cascade of signaling events that lead to the growth and proliferation of these cells. Progesterone also plays a role in the growth of fibroids, but estrogen is the primary hormone responsible for promoting their development.
**Why Each Wrong Option is Incorrect**
**Option A:** While progesterone does play a role in the growth of fibroids, it is not the hormone that primarily promotes their development.
**Option B:** Human chorionic gonadotropin (hCG) is a hormone produced during pregnancy, and while it can stimulate the growth of fibroids, it is not the primary hormone responsible for their development.
**Option C:** Relaxin is a hormone produced during pregnancy that helps to relax the pelvic muscles, but it is not directly involved in the growth of fibroids.
**Clinical Pearl / High-Yield Fact**
Uterine fibroids are more common in women who are obese, have a family history of fibroids, or are taking hormone replacement therapy. Estrogen levels are higher in women who are obese, which may contribute to the growth of fibroids.
**Correct Answer: A. Estrogen**