Linea nigra in pregnancy is due to the stimulation of this hormone?

Appeared in: AIIMS Raipur NO - 2019 (Shift-2)

Explanation

Linea nigra, the dark vertical line on the abdomen seen in pregnancy, is a result of hyperpigmentation.
This hyperpigmentation is primarily caused by increased levels of Melanocyte-Stimulating Hormone (MSH), which is produced by the placenta.
MSH stimulates melanocytes, the skin's pigment-producing cells, to increase melanin production.
While estrogen and progesterone also contribute to skin darkening, MSH is the principal hormone driving this specific change.

Option A: Human chorionic gonadotropin (hCG) is primarily responsible for maintaining the corpus luteum in early pregnancy to ensure progesterone production. It is not the main driver of skin pigmentation.
Option B: Although progesterone contributes to the general hyperpigmentation of pregnancy, Melanocyte-Stimulating Hormone (MSH) is the primary hormone that directly stimulates melanocytes to produce more pigment, causing linea nigra.
Option C: Human placental lactogen (hPL) is mainly involved in maternal metabolism, acting as an insulin antagonist to ensure a steady supply of glucose to the fetus. It does not play a role in skin pigmentation.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal basis of skin changes in pregnancy as background academic context rather than a clinical decision trigger.
Nurses should reassure pregnant clients that linea nigra is a normal, common, and temporary skin change that does not indicate any underlying problem.
Patient education should include advising the use of broad-spectrum sunscreen, as other pregnancy-related hyperpigmentation like chloasma (melasma) is exacerbated by sun exposure.
It is crucial to differentiate physiological changes like linea nigra from pathological skin lesions. Any new, rapidly growing, or irregularly shaped pigmented lesion should be evaluated by a healthcare provider to rule out melanoma.

How to Approach the Question

First, identify the key term in the question: 'linea nigra'.
Recall or deduce that linea nigra is a form of skin darkening or hyperpigmentation.
Connect the concept of skin pigmentation to the hormone that controls it. The name 'Melanocyte-Stimulating Hormone' directly indicates its function of stimulating melanocytes (pigment cells).
Evaluate the functions of the other hormonal options. hCG is for pregnancy detection/maintenance, progesterone for uterine support, and hPL for maternal-fetal metabolism.
Conclude that MSH is the most direct and primary cause of the pigmentation described as linea nigra.

Concept Tested & Keywords

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E6 Obstetrics Williams p. 40-59

Practise the full AIIMS Raipur NO - 2019 (Shift-2)

Attempt every question from this paper in a timed mock, then review the full solution for each one.