History of Pregnancy Testing

Be thankful for the modern wonder of the home pregnancy test, because as Sarah Tennant discovers, in days gone by confirmation of conception was far from convenient.

For drama and suspense in real life or TV, you can’t go past a pregnancy test. Those few minutes of waiting alone in the bathroom, staring at the small plastic doohickey that will predict your future, are a ritual millions of women have shared. According to a 2012 UK poll, 19% of mothers keep their positive pregnancy tests as a memento. Some of them even post a pic of the telltale blue or pink line on Facebook, leading to complex discussions about the etiquette of sharing urine related photos.

So it’s strange to think that only a few decades ago, pregnancy tests didn’t exist at all. In fact, for most of history, women didn’t ‘find out’ they were pregnant in a single definitive moment; instead, their suspicions coalesced over the course of several weeks or months.

Surprise, it’s a baby
Or sometimes, they didn’t. It wasn’t unheard of for women to not experience, or at least not recognise, the signs of pregnancy until it was far advanced. Women with irregular periods might not notice missed menstruation, an anterior placenta might muffle the baby’s kicks and symptoms such as morning sickness, tiredness and sore breasts skip some lucky women anyway. In fact, even in modern, post-sex-ed times, American reality TV managed to eke four seasons out of a show entitled 'I Didn’t Know I Was Pregnant' featuring dramatic re-enactments of women going unexpectedly into labour.

You might be tempted to think it didn’t matter too much back then; women weren’t exactly rushing for the folic acid and prenatal appointments anyway. But in fact, women throughout history have been desperately keen to diagnose pregnancy as soon as possible. Many cultures believed pregnant women should abstain from sex, or from participating in certain religious rituals; others fed mothers-to-be up with special, nourishing foods. And of course, there were times when diagnosing pregnancy promptly could mean a child born in wedlock rather than out!

The early days
Some of the earliest pregnancy tests we know of hail from ancient Egypt. One test involved getting potentially-pregnant women to water wheat and barley seeds with their urine. The idea was, if the seeds failed to germinate, she wasn’t pregnant. If the barley sprouted first, she was having a boy; if the wheat sprouted first, a girl.

An Egyptian study (admittedly, a very tiny one) claimed the test had a 70% success rate for determining pregnancy, though not for predicting the baby’s sex.

But the theory behind it isn’t completely cuckoo. Pregnancy urine’s estrogen content promotes plant growth —my mother once worked with an elderly obstetrician who used to collect his patients’ urine samples to water his camellias, back in the early eighties when you could do that sort of thing.

Another not-so-crazy, though somewhat callous, Egyptian test relied simply on triggering morning sickness. If the smell of beer and mashed dates made a woman throw up, voila – she was pregnant.

A more dubious ancient test worked on the principle that the body had ‘open’ and ‘closed’ states, in which the various bodily passages acted like flues in a chimney. When the woman was fertile, or open-wombed, a strong-smelling substance inserted into the vagina would scent her breath. When pregnancy closed the womb, it wouldn’t. This theory appears in several different cultures – the more pleasing version used perfumed linen, but Hippocrates recommended onions and the French used garlic right up until the eighteenth century!

Another test has been disappointingly lost to time. Assyrian women would soak a wooden tampon in herbs before inserting it for a few days; the wood would turn red or green, indicating pregnancy or otherwise. Scientists believe it’s possible this worked, perhaps due to pH changes in the vagina, but as no one’s been able to correctly identify which herbs were used, we’ll never know for sure.

A wee bit of progress
Moving on to the medieval period, the focus shifts back to urine. It would be nice to think that this meant medieval physicians had glimmerings of knowledge about hCG. They didn’t; they were simply convinced that urine was the key to all diagnosis. Under the misleadingly scientific-sounding heading of ‘uroscopy’, medieval pregnancy tests included:
☙ dropping a latch, key or needle into a woman’s urine. If it rusted, she was in the family way.
☙ mixing urine with wine and staring at it (possibly somewhat effective, as the acids in the wine might curdle certain proteins in the urine).
☙ just plain staring at it. Pregnant urine was thought to be a "clear, pale lemon colour leaning toward off-white, having a cloud on its surface.”

Slowly, as the scientific community began getting its act together, pregnancy tests began to rely more on observing the actual patient. In 1700 Jacques Guillemeau claimed that “a pregnant woman gets deep-set eyes with small pupils, drooping lids and swollen little veins in the corner of the eye.” Okay, a little insulting and not accurate, but at least he was trying.

The 19th century did better; observation of pregnant women’s bodies led to a plethora of pregnancy ‘signs’. Chadwick’s sign (discovered around 1836) was a bluish discolouration of the genitals which occurs at 8-10 weeks due to increased vascularisation (development of blood vessels in an organ). Vascularisation also results in softening of part of the cervix – Goodell’s sign. Many others discovered signs related to textural and positional changes in the uterus that could be felt by palpation... possibly. Unfortunately, respectable Victorian ladies weren’t exactly open to having their tummies touched and fondled by male physicians, much less showing them the colour of their cervices.

The hCG discovery
But science marched on, and in 1927 scientists Aschheim and Zondek discovered human chorionic gonadotropin – hCG – a substance which appeared in the urine of pregnant women, and only pregnant women. (Well, okay, and men with testicular cancer.)

What’s more, they found that if hCG-rich urine was injected into a rodent, it would cause the animal to ovulate. Thus, the first clinical pregnancy test – called a bioassay – was born. To ensure the rodents weren’t just coincidentally ovulating, the researchers used prepubescent specimens. Unfortunately, the only way to test for ovulation was to dissect the animal’s ovaries, making this method of pregnancy testing time-consuming, costly and decidedly non-vegan.

Fortunately, someone then realised the same procedure could be used on frogs. As frogs expel their eggs externally when they ovulate, there’s no need to cut them up. The results were also quicker – 48 hours as opposed to five days for mice.

Oddly enough, although rats, mice and frogs were the most widely-used animals for pregnancy tests, bioassays somehow became culturally linked with rabbits – which weren’t used nearly so often. In pop culture, “the rabbit died” became synonymous with “I’m pregnant” – a double misconception, as the poor bunny actually died whether the test was positive or not.

Not tested on animals
By the 1930s, pregnancy books were recommending that women get clinical confirmation of pregnancy.

In the 60s, a new animal-free procedure – the immunoassay – was developed which involved mixing purified hCG and a urine sample with anti-hCG antibodies. If the woman was pregnant, the cells clumped together or ‘flocculated’. A pregnancy testing kit sold to doctors in 1970 took only two hours to show a result.

In 1978, the science was good enough – and the demand high enough – that the first home pregnancy test was produced. It wasn’t as simple as modern versions. The kits, which cost $10 ($36 in today’s money) included sheep’s blood, a test tube stand with a mirror at the bottom to more easily observe flocculation, an eye dropper and sterile water. (Sounds rather fun, actually.) The test boasted 97% accuracy for positive results and 80% accuracy for negative.

Today’s home pregnancy tests are officially ‘sandwich’ (or ‘indirect’) ‘enzyme-linked immunosorbent assays’, or ELISAs; a fancy way of saying ‘hCG makes the line change colour’.

And the modern pregnancy test is pretty darn cool. It’s easy to use; it takes only a few minutes; and the results can be anything from a discreet pink or blue line to a plus sign or a digital “You’re Pregnant”. And the sensitivity of tests just keeps increasing – 25 mIU/hCG is standard for ‘early’ pregnancy tests, but you can now buy tests that detect levels as slight as 10mlIU/hCG, allowing you to test mere days after ovulation.

Yet these advances have come at a price, literally. An early-response pregnancy test from the chemist will set you back $20. You could buy a lot of wheat and barley for that. It’s cheaper to purchase tests online, especially in bulk, if you can stand the shipping time. Better yet, ask around at midwifery clinics and birth centres. Some will test you for free, on the spot and a few will give you tests to take home.

Whereupon you can post a picture of the results on Facebook. And if anyone complains, tell them to be grateful it wasn’t a dead rabbit.