The secretion of human chorionic gonadotropin (hCG) by the placenta is maximal during?

BSF Staff Nurse - 2015

Obstetrics & Gynaecology

Easy

Appeared in: BSF Staff Nurse - 2015

Explanation

Human chorionic gonadotropin (hCG) is a hormone produced by the syncytiotrophoblast cells of the placenta after implantation.
Its primary role in early pregnancy is to maintain the corpus luteum, which continues to produce progesterone to support the uterine lining.
hCG levels rise exponentially in the first trimester, doubling approximately every 48 hours.
The secretion reaches its maximum or peak level around 8 to 12 weeks of gestation, which corresponds to early gestation.
Following this peak, hCG levels decline significantly by 16-20 weeks and then remain at a lower, stable plateau for the remainder of the pregnancy.

Option A: During late gestation (the third trimester), hCG levels have long passed their peak and are stable at a much lower concentration.
Option B: During mid-gestation (the second trimester), hCG levels are actively declining from their first-trimester peak and settling into a low plateau.
Option C: Implantation is when hCG secretion begins. At this stage, the levels are very low and just starting to rise, so they are far from their maximum.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Hormonal changes in pregnancy, specifically the secretion pattern of human chorionic gonadotropin (hCG) as background academic context rather than a clinical decision trigger.
The rapid rise of hCG in early pregnancy is the biological principle behind urine and blood pregnancy tests, allowing for early confirmation of pregnancy.
Serial monitoring of hCG levels is a critical nursing and medical tool to assess the viability of an early pregnancy. A slower-than-expected rise or a fall in levels can indicate an ectopic pregnancy or an impending miscarriage, prompting urgent evaluation.
What if? - If a patient's hCG levels are found to be abnormally and persistently high for their gestational age (e.g., over 100,000 mIU/mL after the first trimester), it raises suspicion for gestational trophoblastic disease (molar pregnancy) and requires immediate ultrasound investigation.

How to Approach the Question

This is a factual recall question about the hormonal physiology of pregnancy.
First, identify the key hormone (hCG) and the question's focus (maximal secretion).
Recall the typical pattern of major pregnancy hormones. Remember that hCG is often called the 'early pregnancy hormone' because its main job is to maintain the corpus luteum at the beginning of gestation.
Visualize the characteristic curve of hCG levels: a very sharp, early peak followed by a decline to a lower, stable level.
Evaluate the options against this pattern: 'Implantation' is too early (this is the start of the rise, not the peak). 'Mid gestation' and 'Late gestation' are too late (this is after the peak, when levels are low).
Conclude that 'Early gestation' is the only option that correctly identifies the period of the peak.

Concept Tested & Keywords

Concept Tested: Hormonal changes in pregnancy, specifically the secretion pattern of human chorionic gonadotropin (hCG).
Stem keywords: human chorionic gonadotropin, hCG, placenta, maximal secretion
Lead-in keywords: maximal during

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E6 Physiology Guyton 4SAE Part 3 p. 58-60

E6 Obstetrics Williams p. 3