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Pregnancy Test Q&A

Sometimes women wonder about certain aspects of taking a pregnancy test. Not so much whether to have one or not, but whether there are things that can influence the test. In this article we will attempt to address some of the basic questions in a way that will be helpful. Although we don't go into great detail on how pregnancy tests work, we will discuss things like pregnancy test accuracy and the different aspects of the test itself.

Q. I have an IUD - will it affect my pregnancy test?

A. A pregnancy test looks for the hormone human chorionic gonadotropin (hCG), the hormone that is only present in pregnant women. An intrauterine device (IUD), even if it has hormones in it, shouldn't change the results of the pregnancy test, since hCG is only detectable during pregnancy. As an aside, if you are having pain or bleeding or nausea check in with the doctor. Sometimes the hormones in the IUD can trigger such symptoms.

Q. Will the medicine I am taking affect my test?

A. If you are taking fertility drugs, then there is a chance your pregnancy test will be affected. Drugs used in connection with infertility have levels of hCG in them and are the only medications that are really known to affect pregnancy tests. In the case of fertility treatments, your doctor will want you to wait until the medications have cleared your system (they'll give you a time frame) before you take a pregnancy test.

Contraception methods like birth control pills do not affect a pregnancy test.

Q. What is the evaporation line on a pregnancy test?

A. Each manufacturer of pregnancy tests will give you a time limit in which to read your test. It is usually stated very clearly in the instructions that come with the test kit. Usually, the time allowed for a correct reading is between 10 and 30 minutes after the urine test. The evaporation line is only found on urine pregnancy tests and occurs when the test is read after the allotted time frame. Using a urine pregnancy test and letting it sit too long is about the only time a woman will experience an error on a pregnancy test. Digital pregnancy tests read out differently and the risk of a false positive is virtually eliminated when you use one.

Q. What if I take the test too early - is there a chance it will be wrong?

A. Today, pregnancy tests are more sensitive than ever and it is possible for a woman to have a positive pregnancy test within a week of ovulation, which is about a week before a missed period. With a urine pregnancy test, the amount of hCG in the urine is the criteria for determining pregnancy and if concentrations are not high enough, you may get a negative result, even if you are pregnant. It is best to wait until you've missed your period before taking a urine test in order to get pregnancy test accuracy. If it comes up negative, wait a few days and retest.

On the other hand, if you do decide to take a urine pregnancy test before you miss a period and it comes up positive, it means that hCG has been detected in your urine and you are pregnant.

Q. I took a pregnancy test and it was negative and then it came up positive later on. Does that mean I'm pregnant?

A. Most pregnancy tests have a limited amount of time in which you are supposed to read them. Usually it ranges from only a few minutes all the way to 30 minutes. However, if you are like many women, you may keep the test around for half a day and look at it past the specified time. Now the line appears positive. That's because the evaporation line is now exposed. This does not indicate a positive result. If you are surprised by the negative result or if you took the test prior to missing your period, wait a while and try again.

Q. If the line is lighter or sort of faded, is it still positive?

A. Any line, light or dark, is considered to be a positive on a pregnancy test - even if the line is lighter than the control line on the stick. The important factor is that the test is read within the right time frame. If you've read it within the allotted time and the line appears, light or dark, it's positive.

Learn more:

Find out about the different pregnancy tests and how they work by clicking here.