Have you ever wondered how the neat and accurate pregnancy tests we use today first began?
Ancient Egypt
It is hard to believe that oldest descriptions of pregnancy tests come from ancient Egypt. Women who thought they were pregnant would urinate on wheat and barley seeds. If the wheat grew, they believed the woman was having a girl however, if the barley grew, they were having a boy. If neither sprouted the woman wasn’t pregnant! Scientists tested this in the 1970s and found that the urine of pregnant women did indeed promote growth!
For several hundred years there were theories surrounding a woman’s urine. ‘Piss prophets’ in the Middle Ages claimed to detect illnesses as well as pregnancy.
Many doctors suggested that “internal secretions” by certain organs were crucial to an understanding of human biology. Ernest Starling named these chemical messengers “hormones.” This began a whole series of discoveries.
In the 1920’s several scientists recognised that there was a specific hormone only found pregnant women, we now know this hormone to be human chorionic gonadotrophin (HCG), this is the hormone a pregnancy test looks for.
A test was devised to diagnose pregnancy. However, this involved injecting a woman’s urine into a female rat. The rats ovulated if the woman was pregnant. During the 1930’s laboratories expanded this type of test. They learned about HCG and luteinising hormone (LH), but sadly all these tests involved the sacrifice of mice, rats, toads, and rabbits.
The development of immunoassays in the 1970’s meant that thankfully no more animals were used for experiments. This test used purified HCG, antibodies were directed towards the HCG, they would pull together in a pattern which was seen in the result.
In 1976 the first home pregnancy tests became available. They were more accurate for positive results than for negative! Meaning a negative test result could not be trusted and needed two hours before the result could be read.
In the last 30 years pregnancy tests have developed into a lateral flow simple 3-minute test. The latest lateral flow tests simply require a woman to dip a test stick in her urine. Any HCG present in the urine will bind to colour-labelled specific antibodies and travel along a test strip by capillary action. Immobilised antibodies under a result window trap the colour-labelled HCG complex causing a line or positive symbol to appear. In the absence of HCG this line or cross would not appear, indicating a negative result.
Present day
As the tests became more widely available the cost fell, meaning it could be a test available to everyone. The availability of pregnancy tests has improved care for women, early knowledge for those who have had an ectopic pregnancy previously or those with a pre-existing medical condition. But equally as important, a negative result can provide the knowledge or reassurance of no pregnancy. Thankfully science has come a long way since women had to wee on barley and wheat!