CourseCourseQ BankQuestion BankDocsDocuments

D3.1.17 (HL)—Pregnancy testing

Pregnancy tests detect HCG, a hormone secreted by the embryo that maintains the corpus luteum and progesterone secretion early in pregnancy.

Syllabus
First assessment 2025
Objective
D3.1.17
Level
HL

Exam analysis

Chance of appearing12%of analysed past papers
Latest appearanceMay 2024
Most common paperPaper1
Typical marks1

Common command terms

  • Identify

Scoring notes

Common mistake
Placing HCG production in the pituitary, corpus luteum or ovary instead of the embryo.

Recent exam appearances

May 2024Paper1 ["HL"] · TZ140[ 1 ]D3.1.17 (HL)—Pregnancy testing
May 2023Paper1 ["HL"] · TZ137[ 1 ]D3.1.17 (HL)—Pregnancy testing
November 2022Paper1 ["HL"] · TZ040[ 1 ]D3.1.17 (HL)—Pregnancy testing
May 2022Paper1 ["HL"] · TZ240[ 1 ]D3.1.17 (HL)—Pregnancy testing
May 2022Paper1 ["HL"] · TZ140[ 1 ]D3.1.17 (HL)—Pregnancy testing
Practice this objective

Coverage 2013–2024 · Updated 16 Jul 2026

Pregnancy Tests Detect a Hormone after Implantation

HL only

Pregnancy tests detect human chorionic gonadotropin (hCG) using monoclonal antibodies that bind specifically to the hormone.

The early embryo or developing placenta secretes hCG after implantation. hCG maintains the corpus luteum, allowing progesterone secretion to continue, and enters maternal blood and urine.

Urine moves along the test strip → labelled anti-hCG antibody binds hCG if present → the complex is captured by another anti-hCG antibody at the test line → a control line confirms flow and reagent function.

A test taken before urine hCG reaches the detection threshold can be negative even if implantation later produces a detectable concentration.

The test detects hCG, not the embryo directly. A control line does not indicate pregnancy; it indicates that the strip operated correctly.

Pregnancy testing

HL only

Assessment in practice

1 marks
How it is assessed

This objective is assessed through multiple choice, commonly using Identify.

Command terms

Identify

What earns marks

Build the answer around this relationship: HCG is secreted by the embryo during early pregnancy.

Watch for

Placing HCG production in the pituitary, corpus luteum or ovary instead of the embryo.

Representative question

Question 1

[Maximum number: 1]

What is a function of human chorionic gonadotropin (HCG)?

A

To stimulate the corpus luteum to produce progesterone during early pregnancy

B

To stimulate contraction of uterine muscles at the onset of birth

C

To inhibit the production of progesterone and prevent menstruation during pregnancy

D

To prevent polyspermy during fertilization in the fallopian tubes

Retrieve the HL Reproduction Route

HL only

HL D3.1 is about ordered mechanisms and evidence judgment: endocrine control, gametogenesis contrast, one-sperm fertilization, early embryo stages, hCG detection, placental exchange, birth feedback, and HRT evaluation.

  • GnRH drives pituitary FSH/LH and sex-hormone production
  • spermatogenesis gives four sperm; oogenesis gives one ovum and polar bodies
  • acrosome entry, cortical block, cleavage, blastocyst, endometrium
  • hCG, placenta, childbirth feedback, and HRT risk-benefit evaluation

HL Human Reproduction

HL only

HL D3.1 moves from reproductive events into control and evidence. The strongest answers keep sequences in order: endocrine axis at puberty, gametogenesis outcomes, fertilization blocks, blastocyst implantation, hCG testing, placental exchange, childbirth feedback, and HRT evaluation.

  • Explain HL mechanisms in order, especially hormone pathways and early-development stages.
  • Compare gametogenesis and fertilization mechanisms using precise structural terms.
  • Evaluate HRT by weighing symptom benefits against risks and evidence quality.

Concept essentials

  • HCG is secreted by the embryo during early pregnancy.
  • HCG maintains the corpus luteum so progesterone secretion continues.
  • Pregnancy tests detect HCG using monoclonal antibodies.