Video:Are Home Pregnancy Tests Accurate?

Transcript:Are Home Pregnancy Tests Accurate?

Hello I'm Dr. Stuart James Fischbein. I'm a fellow of the American College of Obstetrics and Gynecology. My website is www.BirthingInstincts.com and I'm here today on behalf of About.com to talk to you about whether you can rely on your home pregnancy test and are they accurate?

Accuracy of At-Home Pregnancy Tests

The answer to that question is very short and very simple: Yes - home pregnancy tests are very accurate, once you get to the point where you are at least 10-12 days from the point of conception, or about the time that you missed your menstrual period. By that point, unless your urine is extremely dilute, the likelihood that your pregnancy test is going to be positive on a commercially available pregnancy test bought at your local drug store is extremely high. That's why they ask you usually to use your first morning urine, because your urine is a little more concentrated, so you're going to get a better result than if you've been drinking water all day long and then try to use that urine. But ultimately, you can rely heavily on these tests that by the time of your missed menstrual period if you do a home pregnancy test and it's positive, you can trust that it is.

Supplies in Home Pregnancy Tests

I notice that these kits usually give you 2 or 3 of them in there because everybody wants to do 2 or 3 just to be certain. But if one is pregnant, if one is positive and the other one isn't positive, that would be very, very unusual. Of course if that's the case then the final arbiter might be going to see your practitioner and getting a urine or a blood pregnancy test at his office or her office because they tend to be very, very accurate. And blood tests can be extremely accurate, but of course they are more expensive.

How Do At-Home Pregnancy Tests Work?

The chemical hormone that's being tested in your urine pregnancy test is called hCG or human chorionic gonadotropin. This is the hormone that's made by the developing placenta. A lot of people think it's made by the fetus, but it actually isn't made by the fetus at all; it's made by the placenta. So by the time 2 weeks after conception has occurred, the placenta is already big enough and implanted into the uterus that there is a transfer of this hormone across the placental barrier into the mother's blood and therefore it is in the blood stream, which is filtered through the kidneys, which then goes into the urine in enough concentration by two weeks after conception that it's going to show up on your pregnancy test.

So hCG is the chemical that these tests are testing for. It's very unlikely that there is an alternative source of hCG. There are some very, very rare things not worth mentioning, and if you have a positive pregnancy test, go see your physician.

Again, I'm Dr. Stuart James Fischbein. Thank you so much for watching. If you would like to get more information please visit us online at About.com.