hCG is the “pregnancy hormone” that the placenta produces when a woman is pregnant. It is present in the blood and urine of the pregnant woman and it is this hormone that the home pregnancy test needs to detect in order to reveal a positive result. Some women think the most accurate pregnancy test is the one that’s going to tell them they’re pregnant the soonest but actually the most accurate pregnancy test is the one that’s going to tell the truth whether it’s positive or negative
A urine sample is the most common method used to test for pregnancy. Whether a home pregnancy test is used or the woman goes to the doctor’s office for a pregnancy test, the common factor is the detection of hCG in the urine.
There are two types of blood tests used to test for pregnancy. One is called a Qualitative blood test and this checks for the presence of hCG. The other one is called a Quantitative blood test and it checks to see how much hCG is present. This kind of blood test, which is the most accurate pregnancy test would aid the doctor in determining how far along a pregnant woman is but it would also alert the doctor to a positive pregnancy test because while the urine tests won’t detect a minute amount of hCG, the quantitative blood test will.
Some women buy a home pregnancy test and try to find out if they’re pregnant even before they have missed a period. Science has come a long way even making it possible to find out at home but even then the best it has gotten for the home pregnancy test is testing the first day of the missed period.
While the blood test can find any amount of hCG that’s present in the blood, the urine test and especially the home version can only find hCG once it has reached a certain level. Since hCG levels double about every 2 days, the most accurate pregnancy test is going to be the one that will detect the level of hCG at the time the test is administered.
At one day late, there is a home pregnancy test called First Response that will detect hCG at 12.5 mIU (thousand international units). That is about the smallest amount any home pregnancy test is going to detect and many of them won’t detect the hCG until there is 25 mIU present.
This is why you may get a negative result when you are really pregnant but as soon as the hCG level rises, the pregnancy test will be positive. Thus, the most accurate pregnancy test may depend on the timing because once the hCG is present in a detectable amount, whether it is a blood or urine test, it will be detected.