A pregnancy test is carried out to confirm whether or not a female is pregnant by examining her blood or urine. Pregnancy testing has become more advanced in technology and is now more accurate and quick. But it has taken a long time to reach what we see now. Let’s examine how far we have come to date.
Talking about the first pregnancy test, an ancient Egyptian papyrus described ways to find out the pregnancy and the sex of the baby by urinating on wheat and barley. If barley sprouts, the baby is male, and if wheat grows, it is a female baby. The urine of non-pregnant ladies and men cannot promote the growth of both barley and wheat. A high level of estrogen in pregnant women's urine was postulated to be the reason for the growth.
Another method of spotting pregnancy was by observing the color of the urine, and it was happening in the 17th century. As per NIH (national institute of health, U.S ‘s medical research agency)pregnancy urine, it was described as “clear, pale lemon color, leaning toward off-white, having a cloud on its surface." This was thought to be due to some crystals and bacteria in the urine.
Coming to nineteenth century, when scientist couldn’t develop reliable test, pregnancy was determined by observing the bodily signs and symptoms like morning sickness and vomiting.
In the 1920s, scientists described a test called the A-Z test, which determines the presence of a hormone called Human chorionic gonadotropin (hCG) in the urine. When a woman is pregnant, The placenta produces hCG, which thereby helps to secretes progesterone by stimulating the corpus luteum. Progesterone is a hormone that aid to maintain the pregnancy. A woman’s urine is injected into an immature rodent, and if the woman is pregnant, the rodent shows an estrous reaction(i.e. heat; it indicate that the female has sexual desires and can conceive), which also indicates the presence of hCG hormone. Otherwise, there won’t be any reaction.
The 1960s were the period when the 'A-Z test’ was replaced with the hemagglutination inhibition test, which is an immunoassay to determine hCG in urine due to cost, speed, and sensitivity issues.
Then later on, in the 1970s, more research was undertaken to detect pregnancy as soon as feasible. As a part of it, Wampole's two-hour pregnancy test came to the scene, which was a laboratory test. Then, in the mid-1970s, radioimmunoassay came into existence for pregnancy testing. In late 1970s, the FDA approved the first home pregnancy test kit in the US.
As a part of upgrading pregnancy testing, new antibodies and enzyme labels were developed during the 1990s.
After a great deal of research was conducted, current pregnancy tests were developed, which ranged from a thin blue line that indicated pregnancy to the most modern digitalized test displaying either "pregnant" or "non-pregnant.
References
https://www.aacc.org/cln/cln-industry-insights/2020/pregnancy-testing-through-the-ages
https://history.nih.gov/display/history/Pregnancy+Test+Timeline#:~:text=1350%20BCE
https://www.smithsonianmag.com/smart-news/egyptian-papyrus-reveals-old-wives-tale-very-very-old-indeed-180970066/