The role of human placental lactogen is:
**Core Concept**
Human placental lactogen (hPL) is a hormone produced by the placenta during pregnancy, playing a crucial role in fetal growth and development. It is a member of the growth hormone-prolactin family and exerts its effects by binding to specific receptors in the fetus and mother.
**Why the Correct Answer is Right**
hPL promotes fetal growth by stimulating the mother's pancreas to produce more insulin, which in turn promotes glucose uptake by the fetus. Additionally, hPL inhibits the mother's insulin sensitivity, thereby preventing excessive glucose utilization by the mother's tissues. This ensures that glucose is redirected to the fetus for growth and development. hPL also promotes lipolysis in the mother's adipose tissue, providing a source of fatty acids for fetal growth.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not accurately describe the primary role of hPL. While hPL does have some effects on maternal metabolism, its primary role is to promote fetal growth and development.
* **Option B:** This option is incorrect because it is too narrow in scope. While hPL does play a role in glucose metabolism, its effects extend far beyond just glucose regulation.
* **Option C:** This option is incorrect because it is not a well-established function of hPL. While hPL may have some effects on maternal thyroid function, this is not its primary role.
**Clinical Pearl / High-Yield Fact**
hPL levels rise throughout pregnancy, peaking at around 36 weeks of gestation. Elevated hPL levels are associated with fetal growth restriction and other pregnancy complications.
**Correct Answer: C. Promotes fetal growth by stimulating maternal insulin production and redirecting glucose to the fetus.**