Which hormone is responsible for performing placental function during first 8-10 weeks of pregnancy?

AIIMS Raipur NO - 2019 (Shift-1)

Obstetrics & Gynaecology

Easy

Appeared in: AIIMS Raipur NO - 2019 (Shift-1)

Explanation

Human chorionic gonadotropin (hCG) is secreted by the syncytiotrophoblast cells of the developing placenta shortly after implantation.
The most crucial function of hCG in early pregnancy is to prevent the involution (breakdown) of the corpus luteum.
By maintaining the corpus luteum, hCG ensures the continued secretion of progesterone and estrogen, which are vital for sustaining the uterine lining and the pregnancy itself.
This 'rescue' of the corpus luteum by hCG bridges the hormonal gap until the placenta is mature enough to produce sufficient progesterone and estrogen on its own, a transition known as the luteal-placental shift, occurring around 8-10 weeks.

Option B: Progesterone is essential for maintaining the pregnancy, but in the first 8-10 weeks, it is primarily produced by the corpus luteum under the direction of hCG. It is the result of the hormonal signal, not the initial signal itself.
Option C: Luteinizing hormone (LH) stimulates the corpus luteum during the menstrual cycle, but its role is taken over by the more potent hCG after conception. LH levels actually decrease during early pregnancy.
Option D: Similar to progesterone, estrogen is a crucial hormone for pregnancy, but during the initial 8-10 weeks, its production from the corpus luteum is dependent on stimulation by hCG.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation in early pregnancy as background academic context rather than a clinical decision trigger.
The presence of hCG in a woman's urine or blood is the basis for all standard pregnancy tests. Its rapid rise in early pregnancy makes it a reliable marker.
Serial measurement of hCG levels is a critical tool for nurses and doctors to monitor the viability of an early pregnancy. Abnormally low or slowly rising levels can indicate a potential miscarriage or an ectopic pregnancy.
The 'luteal-placental shift' around 8-10 weeks is a critical transition point. Failure of the placenta to produce enough progesterone by this time can result in pregnancy loss, highlighting the importance of this hormonal handover.

How to Approach the Question

First, identify the key components of the question: the specific timeframe ('first 8-10 weeks') and the function ('responsible for performing placental function').
Recognize that 'performing placental function' in this early stage refers to providing the hormonal support (progesterone and estrogen) that the mature placenta will later provide.
Recall the sequence of hormonal events after fertilization: The embryo implants and its trophoblast cells start producing a new hormone.
Differentiate between the 'master signal' hormone and the 'effector' hormones. The question asks for the hormone responsible for the process, which is the master signal.
Consider each option: Progesterone and Estrogen are the effector hormones. LH is from the mother's pituitary and its role is superseded. hCG is the new hormone from the embryo that directs the process.
Conclude that hCG is the primary hormone that orchestrates hormonal support in the first 8-10 weeks by maintaining the corpus luteum.

Concept Tested & Keywords

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