How do home pregnancy tests work?
As a rule all home pregnancy tests work by detecting the presence or absence of a pregnancy hormone, which is called human chronic gonadotropin, or hCG, in the morning urine sample of a woman. The thing is that every women becomes pregnant in the result of her egg’s fertilization by a man’s sperm cell in one of her fallopian tubes (the process of this kind of fertilization is called conception). After 9 days the egg begins to move down the fallopian tube, in which it was fertilized into the uterus and it is to get attached to the wall of the uterus (the process of the egg’s attachment to the wall of the uterus is called implantation). As soon as the implantation process occurs, the placenta begins to develop and it starts to release hCG into the blood. Some amount of hCG occurs in the urine, while during the first week of pregnancy the amount of hCG in the urine of a woman rises drastically, and it gets doubles every 2 days.
Many home pregnancy tests would not tell you accurately if you are pregnant or not if you conduct any of them on the very day, you expect your period to begin. The most accurate result will be somewhere in a week after your missed period.

What is the difference between pregnancy tests, which work by checking urine and those pregnancy tests, which test blood? Which type works better and gives results that are more accurate?
Nowadays it is common to use home pregnancy tests, if you want to get to know whether you are pregnant or not. Nearly every home pregnancy test is private, easy to apply and rather cheap. Already in two weeks after you have had ovulation it is possible to determine if you are pregnant or not with the help of a home pregnancy test kit. There are even some extra sensitive urine tests, which may give you the result as early as one day after your period is missed.
Blood test may only be conducted in a clinical conditions and by your doctor or nurse. There are two types of blood pregnancy tests: the quantitative blood test and the qualitative blood test.
The Quantitative blood test (it is also called the beta hCG test) works by measuring the exact amount of hCG, present in your blood. Thus, it can even distinguish the smallest amount of this hormone, if it is present in your blood sample. This makes the quantitative blood test extremely accurate. So, you may have it done beginning with the 5th day of ovulation.
The Qualitative blood test only checks the presence or absence of the hCG in your blood by giving you “YES” or “NO” answer. This kind of blood test is considered to be approximately as accurate as most urine tests, and it is better to conduct it somewhere after one week of your missing period.
These tests work by picking up hCG earlier then most urine tests do.

How do you conduct a home pregnancy test?
Most home pregnancy test kits include a detailed instruction, and most of them work in the same way. To do some pregnancy tests you will have to hold a stick in the morning urine stream, to do others, you will have to collect your morning urine into a special cup and after that put a few drops of it into some special container with a dropper. Anyway, you are to use only your first morning urine sample (the urine, which has accumulated in the bladder during the night) in order your test would give you the most accurate result.

After you have provided the test and your urine contact, wait for several minutes. Different pregnancy tests’ brands require different amount of time to be waited. Still as soon as the time has passed, you are to look at the “result window”. In case if a line or a plus symbol appears on it, congratulations, you are a future mother now! It does not matter at all how faint the line is, as its colour and vividness depends on the amount of hCG in your urine, and you do realize, that the less term you are expecting, the less amount of this hormone is present in your urine. So, any kind of line, whether it is bold or faint, the result is still positive.

There are also home pregnancy test kits, which have a special “control indicator” in the result window. It is a line or a symbol, which lets you know if the test is working or not. In case if the control indicator does not come out, it means, that the test is not working properly, and there is no need to trust its result.
Most brands will offer you to repeat the test in several days in order to make sure completely, no matter what kind of a result you have obtained at the first time.

How accurate are home pregnancy tests?
You should be aware, that the accuracy of nearly all home pregnancy tests may vary, and the reasons of it may be the following:
  The days, when your menstrual cycle and your ovulation occur, usually differ from month to month;
  The exact day of the fertilized egg’s implantation is not known exactly;
  Each home pregnancy test kit has its own sensitivity in the hCG detecting.