When you begin to experience pregnancy symptoms, you will be eager to take a pregnancy test to confirm your pregnancy. Basically there are two types of pregnancy –blood and urine. Urine tests can be done at home but only a doctor should perform blood tests.
Pregnancy hormone Human Chorionic Gonadotrophin (HCG) gets secreted when a fertilized egg implants in the uterine wall. This is why it is recommended that you wait until the first day of your missed period, to take a home pregnancy test— that is about two weeks after conception.
Urine tests use monoclonal antibodies. It is a man made molecules used in many laboratory tests, to test for HCG. The home pregnancy sticks generally have two line- one is a control line which you will see whether you are pregnant or not, the other line contains the monoclonal antibodies. On soaking the stick in urine, if there is HCG present in your urine, it will react with the monoclonal antibodies, and cause color change, causing the second line to appear. Intensity of the color line will vary depending on the amount of HCG.
Blood tests for pregnancy can be of two types:
Qualitative HCG Test: Performed in a laboratory, this test only measures the presence or absence of HCG in blood—thus you will get a specific yes or no answer.
Quantitative HCG Test: Sometimes called the Beta HCG blood test, it measures the amount of HCG in the blood. The advantage of this test is that it can detect even low levels of HCG, thus can given a positive result, than the other test.
How to get accurate results in home pregnancy tests?
First of all, make sure that you read all the instructions that come with the home pregnancy test carefully. Take note of the test reading time given in the test instructions because if they’re read too early or too late, some tests could give a false reading. In fact a common mistake that women usually make is that they wait too long, resulting in a line appearing, thus interpreting it as a positive result. But it is actually a evaporation line formed as the urine on the test dries
Using the first urine of the day in the morning will give the best result, as the urine is less diluted and if there is any HCG present it will be more concentrated. But if you plan to take the test during the day make sure that there is limited intake of fluids for few hours beforehand. Thereby you can be sure that there are concentrated HCG levels (if present) in urine.
Which one is the best test for you?
Few factors should be taken into consideration on choosing a home pregnancy test. Some tests are ultra sensitive and can detect even very low levels of HCG (up to 12.5 mIU) in your urine. This test is the best choice if you want to know it as soon as possible. But one of its disadvantages is that if you have recently had a miscarriage or recently given birth, you may be prone to false positives. In such cases, the test that will detect a high level of HCG (100 mIU) is a better choice. There are also digital home pregnancy tests that check HCG (50 mIU or higher) and just say if you are pregnant or not pregnant.
When the results are read on time and all the instructions are correctly followed, the home pregnancy tests can be about 97% accurate.
What all factors could result in false positive?
Drug Interference: Some drugs contain the pregnancy hormone Human Chorionic Gonadotropin (HCG) and if you are taking one of these, false positive pregnancy test can result. If you are having infertility treatments and have had a shot of HCG, you should not take a pregnancy test until you are sure the shot is out of your system.
Chemical Pregnancy can result in early miscarriage and because many pregnancy tests are highly sensitive, they can sometimes detect these pregnancies even though they’ve already ended. But when this occurs, woman will get her period as normal.
Evaporation Lines, is not exactly a technically error but result of user error, when women make the common mistake of waiting too long when reading the test. This could result in a line appearing which is actually an evaporation line created as the urine on the test dries.
If you have any doubt about the accuracy of the home pregnancy test that you have taken, you should see a doctor for a pregnancy blood test. These tests are more sensitive and can give you an accurate reading just one week to 12 days after conception.