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Evolution of Pregnancy Testing Methods
Aug 3, 2024
Lecture: History and Science of Pregnancy Tests
Ancient Pregnancy Tests
Date
: 1350 BC
Location
: Ancient Egypt
Method
: Urinate on wheat and barley seeds
If either sprouts, the woman is pregnant.
If wheat sprouts faster, it's a girl.
If barley sprouts faster, it's a boy.
Modern Study (1963)
:
Found 70% accuracy in predicting pregnancy
Could not reliably determine the sex of the baby
Hypothesis
: Pregnant women's urine contains more estrogen, promoting seed growth.
Modern Pregnancy Tests
Hormone Detected
: HCG (Human Chorionic Gonadotropin)
Produced in the early stages of pregnancy
Prevents the shedding of the uterus lining
Supports placenta formation
How Over-the-Counter Tests Work
Application
: Urine is applied to the strip.
Fluid Movement
: Urine travels up absorbent fibers through three zones:
Reaction Zone
:
Antibodies (AB1) attach to any HCG in the urine.
Enzyme linked to AB1 activates dye molecules.
Test Zone
:
More antibodies (AB2) bind to HCG.
HCG is sandwiched between AB1 and AB2, activating dye to show results.
Control Zone
:
Confirms the test's functionality.
Unbound AB1 enzymes activate dye if present.
Reliability and Issues
False Negatives
:
Low HCG levels (too early in pregnancy)
Diluted urine samples (recommendation to test in the morning)
False Positives
:
Sources of HCG other than pregnancy (IVF injections, ectopic pregnancies, certain cancers)
Possible for men to get a false positive
Doctor's Confirmation
:
More sensitive and quantitative tests
Exact HCG levels determined from blood tests
Scientific Method in Pregnancy Tests
Pregnancy tests demonstrate the scientific method:
Ask a question
Perform a controlled experiment
Analyze results to check hypothesis
Modern tests provide quick results without waiting long periods.
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Full transcript