Pregnancy Test Results:Depending on the design of the test, the pregnancy test results may be simpler or harder to read. A test that has enough contrast between the line (or symbol) and the background makes the results easier to interpret. Some brands indicate that an evaporation line may appear if the test is left to sit past a certain time frame; this line may make it more difficult to accurately interpret the test results
Negative Test Results:A home pregnancy test is more likely to yield a false–negative result (meaning, that you really are pregnant) rather than a false positive result (the test says your pregnant when you are not).
A false-negative test result can occur if:
- Your urine is diluted - Many tests suggest that you perform the test in the morning, right after you wake up. This is because your urine is usually the most concentrated at this time. If you drink too much liquid before performing the test, you may end up with an inaccurate result as well.
- You have performed the test too soon - In order to at least have the possibility of an accurate result, you should wait at least a day after your missed period (because a home pregnancy test cannot detect a pregnancy any sooner than that). However, to decrease the chances of a false-negative result, it is better to wait seven days after your period was due.
- You have timed the test incorrectly - It is important that you perform the pregnancy test within 15 minutes after collecting a urine sample. Make sure that you follow the test’s instructions as to how long it takes to analyze the results. If you check the results too soon (before the prescribed time period), the test result may appear to be negative.
Positive Test Results:
Typically, if you receive a positive result (even if it is very faint), this indicates that you are pregnant. It is possible to obtain a false-positive result (the test is positive, but you are really not pregnant) – though this happens very rarely.
You may end up with a false-positive if:
- You are taking a prescription medication that contains hCG, such as Pregnyl, A.P.L., Profasi, Chorex, Novarel, or Ovidrel or the medication promethazine (used as an antihistamine in combination cough and cold products to treat allergy symptoms and to treat nausea or vomiting from illness or motion sickness).
- You have traces of blood or protein in your urine.
- You have used an expired or damaged pregnancy test.
- You are currently taking diuretics.
- You had what is known as a chemical pregnancy. This means that a fertilized egg did implant into your uterus and developed just enough to trigger the production of hCG, but then, for whatever reason, stopped developing. Typically, about 30 to 50 percent of all fertilized eggs end up as chemical pregnancies because of abnormalities or other reasons that make further development impossible. When this occurs, most women will end up getting a period (though it may be a few days later or heavier than usual). The higher likelihood of a chemical pregnancy to occur is another reason why it may be better to wait at least a week after your period is due to take a home pregnancy test.
Where to Get a Pregnancy Test:
Most grocery stores, drug stores, and websites sell home pregnancy tests over the counter (without needing a prescription). Depending on the brand and how many tests come in the box, tests can cost between $4 and $20. Read the package carefully as some may contain 2 tests, so these could be a better deal. If you think you may need a second test because you have irregular periods or if you are testing right after a missed period, it is usually a better bargain to purchase a 2-pack than paying separately for another test.
Blood Pregnancy Tests versus Home Pregnancy Tests:
The urine pregnancy tests performed at most doctor’s offices are basically the same kind as the ones found over the counter. The main difference in pregnancy testing is that some health-care professionals will use blood pregnancy tests, which can detect a pregnancy much earlier than urine tests can. Another advantage of a quantitative blood test is that it can reveal the exact amount of hCG in the blood. This is helpful to assess how far into a pregnancy a woman may be or if there is the possibility that a woman may be miscarrying.
What to Do Next:
If you receive a positive result on a home pregnancy test, you should make an appointment to see your health-care professional. You should also see your doctor if you have taken a few home pregnancy tests and have received mixed results. Your health-care professional may perform a blood test or pelvic exam to confirm your positive pregnancy result. The sooner you know whether or not you are pregnant, the sooner you can start to make decisions about your pregnancy.
Consumer Reports. (2006). “Pregnancy Tests Reviews”.
Cole, L., et al. (2004). “Accuracy of home pregnancy tests at the time of missed menses”. American Journal of Obstetrics and Gynecology, Vol. 190(1), 100-105.