Before your period is due, you'll just have fun speculating. Your extreme fatigue might be a sign that you're expecting, and then there's that frequent peeing, and the nausea... but there is only one thing that will confirm (or deny) your hopes with certainty. It's a pregnancy test, of course.
You may be using strips that you'll dip in a small container of urine, or a pregnancy test that will give you several stripes or a plus if it's positive, or you might be using the more modern digital pregnancy tests. If you don't have a pregnancy test at home yet, you can simply go to any pharmacy. You're even likely to find pregnancy tests at your grocery store, or the dollar store.
All the pregnancy tests on the market today have one thing in common. They react to hCG, a hormone that comes from cells that will later form the placenta. This hormone will be present in your blood and urine as soon as the embryo nestles into the lining of your uterus between six and 12 days following fertilization. Finding out whether you are pregnant is easy. Pregnancy tests are readily accessible, not all that expensive, and no animals have to die or suffer so you can find out whether or not you're having a baby. It wasn't always that way, though. Pregnancy tests have been around a lot longer than you may think, but they were not always as accurate as they are today.
Ancient Greeks, Romans, and Egyptians all had their own methods to find out if a woman was expecting. Egyptians poured the urine of a potentially pregnant lady onto barley and wheat, and germination meant she was indeed with child. Hippocrates though women who had missed a period should drink a solution of water and honey.
Stomach cramps were meant to point to pregnancy. (Sounds pleasant, no?) In traditional Asian medicine, doctors took a woman's pulse to figure out if she was expecting a baby. During the middle ages in Europe, "piss prophets" would determine whether a woman was pregnant or not by looking at the color of her pee. Some even mixed wine in with the urine to get better results. Islamic physicians added sulphur to urine to see if it would breed worms.
If so, the woman was pregnant. Most of these techniques demonstrate that people have suspected urine holds the key to determining pregnancy throughout history. Isn't that truly fascinating? I'm sure I don't need to add that these techniques were not all that reliable. By the nineteenth century, doctors started playing around with microscopes. Crystals or bacteria were thought to suggest a woman was pregnant. At this time, scientists also started being more interested in the anatomy of the female reproductive system. Keep in mind that they didn't know anything about hormones yet.
They were discovered in the late 1800s. HCG, human Chorionic Gonadotropin, was discovered in the 1920s. Scientists immediately figured out that testing for the presence of this hormone could determine if a woman was pregnant. The precursor of the modern pregnancy test was developed soon after, using... lab animals! A woman's urine was injected into the veins of a lab mouse or rabbit. A few days after, the unfortunate animal would be killed and her ovaries taken out. The look of the ovaries would reveal whether the "test" was positive or not. Poor animals.
Besides being cruel, these pregnancy tests were quite expensive and labor intensive as well. Lancelot Hogben found a better way, involving a female African clawed frog. We've had these animals as pets before, and they were really cool. These little creatures even appeared to enjoy being stroked. The thought of dowsing them with urine is a little sickening to me, but the "frog test" didn't actually require the frog to die. That's what we call technological advance! Instead, the test result was positive if the frog produced eggs within 24 hours of being bathed in urine. The same frog could be used multiple times, making this a cheaper option. Still, the frogs were relieved of their duty by the late 1950s, when science managed to produce tests that aren't at all dissimilar to the pregnancy tests you'll be taking. The moral of the story? Your pet rabbit, mouse or African clawed frog can breathe a sigh of relief when you run out to Walmart to get a pregnancy test.