A hormone that prevents menstruation and maintains pregnancy by sustaining the function of the corpus luteum… - AIIMS Raipur NO - 2017 (Shift-1)

AIIMS Raipur NO - 2017 (Shift-1)

Obstetrics & Gynaecology

Easy

Appeared in: AIIMS Raipur NO - 2017 (Shift-1)

Explanation

Human chorionic gonadotropin (hCG) is secreted by the trophoblast cells of the embryo shortly after implantation.
Its primary function is to prevent the involution (breakdown) of the corpus luteum at the end of the monthly cycle.
hCG stimulates the corpus luteum to continue secreting progesterone and estrogen.
These hormones maintain the uterine lining (endometrium), thereby preventing menstruation and sustaining the early pregnancy until the placenta can take over hormone production.

Option A: Follicle-stimulating hormone (FSH) is primarily involved in the follicular phase of the menstrual cycle, stimulating the growth of ovarian follicles. Its role precedes ovulation and the formation of the corpus luteum.
Option B: Luteinizing hormone (LH) triggers ovulation and stimulates the formation of the corpus luteum. However, in a non-conception cycle, LH levels fall, leading to the corpus luteum's demise. It does not sustain the corpus luteum during pregnancy.
Option C: Gonadotropin-releasing hormone (GnRH) is a hypothalamic hormone that controls the release of FSH and LH from the pituitary gland. It acts higher up in the hormonal cascade and does not directly act on the corpus luteum.

Visual 1: Diagram - A graph showing the levels of LH, FSH, estrogen, progesterone, and hCG during the menstrual cycle and early pregnancy. This helps visualize how hCG rises after conception as LH falls, taking over the role of supporting the corpus luteum.
Visual 2: Flowchart - A flowchart illustrating the hormonal cascade: Implantation -> Trophoblast produces hCG -> hCG stimulates Corpus Luteum -> Corpus Luteum produces Progesterone -> Progesterone maintains Endometrium -> Pregnancy is sustained.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal regulation of early pregnancy as background academic context rather than a clinical decision trigger.
The presence of hCG is the basis for all modern pregnancy tests. Nurses educate patients on the correct timing and interpretation of these tests.
Monitoring serial hCG levels is a critical nursing role in early pregnancy to assess viability. Abnormally low or slowly rising levels can indicate an ectopic pregnancy or a potential miscarriage, requiring prompt intervention.
What if? If the embryo failed to produce sufficient hCG, the corpus luteum would degenerate, progesterone levels would drop, and the uterine lining would shed, resulting in the loss of the pregnancy (spontaneous abortion), often mistaken for a late menstrual period.

How to Approach the Question

First, identify the key processes in the question: 'prevents menstruation', 'maintains pregnancy', and 'sustaining the corpus luteum'.
Recall the functions of the major reproductive hormones.
Analyze the options: FSH is for follicle growth, LH is for ovulation and initial corpus luteum formation, and GnRH is the 'master' controller from the hypothalamus.
Recognize that a special hormone is needed to signal the body that pregnancy has occurred and to override the normal menstrual cycle.
Connect this special signal to the embryo itself. The hormone produced by the embryo is hCG.
Conclude that hCG is the only hormone listed that fits the description of rescuing the corpus luteum to maintain early pregnancy.

Concept Tested & Keywords

Concept Tested: Hormonal regulation of early pregnancy.
Stem keywords: hormone, prevents menstruation, maintains pregnancy, corpus luteum
Lead-in keywords: is

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