A pregnancy test may let you know if you are pregnant (or not). Here are the answers to common questions about pregnancy tests.
What is a pregnancy test and how does it work?
Pregnancy tests are designed to tell if your urine or blood contains a hormone called human chorionic gonadotropin (hCG). This hormone is made right after a fertilized egg attaches to the wall of a woman’s uterus.
This usually happens — but not always — about 6 days after fertilization. If you’re pregnant, levels of hCG continue to rise rapidly, doubling every 2 to 3 days.
What types of pregnancy tests are available?
Two main types of pregnancy tests can let you know if you’re pregnant: urine tests and blood tests. In this table we list most common Urine Pregnancy tests that are over 99% accurate.
|First Response Early Result Pregnancy Test||First Response Gold Digital Pregnancy Test||PREGMATE 10 Pregnancy HCG Test Strips||Clearblue Digital Pregnancy Test||E.p.t Early Pregnancy Test|
|Accuracy||Over 99%||Over 99%||Over 99.8%||Over 99%||Over 99%|
|Results Time||3 minutes||3 minutes||5 minutes||3 minutes||2-3 minutes|
|When to Test||6 Days sooner than you missed period (5 days before day of the expected period)||6 Days sooner than you missed period (5 days before day of the expected period)||Will work 5 days before your missed period, greatest sensitivity level - 25 mIU/mL||Up to 5 days sooner||Up to 5 days sooner|
|Results||Two lines (even if one is lighter) means your are pregnant; one line means you are not.||You see a "YES +" if you are pregnant or a "NO -" if you are not||Two lines (even if one is lighter) means your are pregnant; one line means you are not.||Results are clearly displayed in words, ‘Pregnant’ or ‘Not Pregnant'||Two lines (even if one is lighter) means your are pregnant; one line means you are not.|
|Costs||$12.98 for 3 tests on Amazon||$12.99 for 2 tests on Amazon||$7.95 for 10 tests on Amazon||$14.98 for 3 tests on Amazon||$8.48 for 2 tests on Amazon|
How does a pregnancy test work?
Pregnancy is truly a life-changing event. Knowing if you are pregnant earlier allows you to make important decisions, such as adopting healthier lifestyle choices. You can begin taking better care of yourself and your baby sooner, in the first critical stages of your baby’s development.
In one study, in 68% of the samples tested, pregnancy could be detected up to 6 days before the day of the missed period.
The ‘stick’ used for a home pregnancy test contains a strip of absorbent fibers. When the stick is dipped into a sample of urine, the urine moves along the fibers in one direction – just like if you dipped a paper towel in water at one end, you would notice the water creeping along the towel as it is absorbed.
There are three special areas along the length of the pregnancy test strip:
1. First is the ‘reaction zone’. In the reaction zone, the absorbent fibers have been impregnated with a specific molecule called an antibody that attaches itself to hCG – and only hCG.
2. As the urine continues to move along the strip, it carries the antibodies – now attached to hCG – to a second zone called the ‘test zone’. This area contains a chemical that reacts with the antibodies from the reaction zone, but only if they are attached to hCG. If hCG is present, a colored dye is released, causing a colored line to appear on the test strip. If the woman is not pregnant, the antibodies will not have any hCG attached to them, and the dye will not be released, therefore no line will appear on the test strip.
3. The urine continues to move along the strip to the third and final zone – the ‘control zone’. This area contains a chemical that reacts with the antibodies regardless of whether or not they have hCG attached to them. A dye is released and a line appears on the test strip. If the ‘control’ line appears but the ‘test’ line does not, the test has worked properly but you are probably not pregnant. If both lines appear, you probably are pregnant because this shows that hCG has been detected in the test zone.
Because hCG is only produced after the embryo has implanted, pregnancy tests can give a ‘false negative’ result if you take one too early. In other words, if you are pregnant but only just, there may not yet be enough hCG in your urine to be detected by the test. If you are trying to get pregnant, it is therefore usually recommended to wait at least until the first day of your missed period, rather than taking a test straight after you had unprotected sex.