The first known pregnancy test was created in ancient Egypt around 1350 BC. According to Egyptians, all you have to do is urinate on wheat and barley seeds and wait. If either sprouts, you’re pregnant. If wheat sprouts faster, it’s a girl but if barley, it’s a boy. In 1963, a small research replicated the test and discovered that it accurately predicted pregnancy with a 70 percent accuracy, albeit it couldn’t consistently determine the baby’s sex. The test worked, according to scientists, since pregnant women’s urine includes more estrogen, which promotes seed growth. Within minutes, modern pregnancy tests provide highly accurate findings.
How do they work?
|Working mechanism of pregnancy test kit, Image credits: nippongene.com|
Over the counter pregnancy tests are all designed to detect one things: a hormone called HCG.
HCG is created in the early stages of pregnancy and initiates a telephone call to the body, telling it not to shed the uterus’ inner lining that month. HCG helps the placenta form, which delivers nutrients from the mother to the fetus, as the pregnancy advances. The test begins when urine is added to the strip’s exposed end. As the fluid moves up the absorbent fibers, it will pass through three distinct zones, each with a distinct function.
When wave hits the first zone, the reaction zone, Y-shaped protein called antibodies will grab onto any HCG. A useful enzyme that can switch on dye molecules is attached to these antibodies, which will come in helpful later on. The urine picks up all of the AB1 enzymes and transports them to the test zone, where the results are shown. Secured to this zone are more Y-shaped antibodies that will also stick to HCG on one of its five binding sites. Scientists call this type of test a sandwich assay. If HCG is present, it gets sandwiched between the AB1 and AB2 enzymes, and sticks to the test zone, allowing the attached dye-activating enzyme to do its job and creates the visible patterns. If there is no HCG, the waves of urine and enzymes just passes on by. Finally, there’s one last stop to make, the control zone.
This stage, like any good experiment, ensures that the test is functioning appropriately. All the unbound AB1 enzymes picked up in zone 1 should end up here and activate more dye, whether they never saw HCG or are extras because zone 1 is overstocked with them. As a result, if no pattern emerges, the test was invalid. These tests are fairly reliable, but they aren’t without flaws.
For instance, False negatives can happen if the HCG concentration isn’t high enough to be detected. After implantation, HCG levels doubled every two or three days, so it may just early to tell and beverages can dilute the urine sample, which is why doctors recommend taking the test first thing in the morning. False positives, on the other hand, can result from various sources of HCG, such as IVF injections, ectopic pregnancies, or diseases such as uterine cancer or testicular cancer. Because of these criteria, one of these tests may be able to identify if a man is pregnant. The best method to find out for sure is to visit your doctor.