Can drug use affect pregnancy test results?
Pregnancy tests work on the simple principle of finding a pregnancy related specific hormone known as the human chorionic gonadotropin (hCG). The human chorionic gonadotropin (hCG) can be found out in a urine or blood pregnancy test. Let us look at what are the different types of pregnancy tests and how drug use can affect them.
What's the difference between a urine and blood pregnancy test?
There are two types of pregnancy tests, the urine and blood tests. Urine tests determine pregnancy two weeks after ovulation, whereas blood tests determine pregnancy six to eight days after ovulation. Blood tests have an upper hand in determining the exact level of human chorionic gonadotropin (hCG) in the blood. Hence, if you wish to determine whether you are pregnant or not, it is always advisable to get a blood pregnancy test done.
Today, many women use a home pregnancy test that is cost effective and very accurate. You can buy a home pregnancy test over the counter from a drug store. The test involves dipping a special stick from the test kit into your urine sample and observing the change in color of the stick. Indications for pregnancy are noted on the kit.
Bloods pregnancy tests can be quantitative as well as qualitative. A quantitative blood pregnancy test (or the beta hCG test) measures the exact amount of human chorionic gonadotropin (hCG) in the blood. This means it can pick up very small amounts of human chorionic gonadotropin (hCG), making it a very accurate test. A qualitative human chorionic gonadotropin (hCG) blood test gives a simple yes or no answer to whether you are pregnant. This test is more like a urine test in terms of its accuracy.
Do drugs affect pregnancy tests?
Most drugs including birth control pills and antibiotics should not affect the result of your pregnancy tests. You should get an accurate result on pregnancy test results if you are on oral contraceptives. The hormones in the pill do not cause a false positive or a false negative result.
In case you are on drugs containing human chorionic gonadotropin (hCG) used for treating infertility, you have a chance of getting a false positive result of pregnancy. This means a positive pregnancy result when actually you are not pregnant.
Clomiphene Citrate (Clomid/Serophene) can interfere with ovulation test results - generally in the form of a false positive. However, Clomid generally causes a false positive only if you perform an ovulation test too soon after taking Clomid - or too early in your cycle. Most drug manufacturers suggest you should not start testing with the ovulation predictor kit until several days after you finish the last dose of Clomid.
Drugs like Profasi, Pregnyl or Novarel may give false positive results if the test is performed within 7-14 days of last shot of the drug. Narcotic drugs such as cocaine, marijuana, heroine, and alcoholic drinks will not alter the result of a home pregnancy test, but you are advised to test when not under the influence of these drugs.
Home pregnancy tests have been found to be around 97-98% accurate irrespective of any drugs taken by the woman as the test relies on finding a specific subunit of human chorionic gonadotropin (hCG) in the urine sample. Hence they are safe to buy over the counter and effective in directing you to your gynecologist as early as possible to do a definitive blood test.
Read about how accurate are blood pregnancy tests as compared to home pregnancy tests.
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