Here are some things that can cause false positives:
- hCG shots for weight loss or as a fertility treatment
- soaps or detergents (This is why most pregnancy tests now tell you to urinate directly on the stick instead of urinating in a cup and then placing the test stick in the urine.)
- medications such as anticonvulsives, Parkinson's disease medications, tranquilizers, certain diuretics, methadone, promethazine
- trophoblastic or germ cell tumors which grow in the reproductive system
- hysterical/ false pregnancy
- leaving the test for too long/ not timing it correctly
- uterine, breast or ovarian cancer
- expired or defective pregnancy test
- evaporation lines (if the lines are barely visible)
- chemical pregnancy/ early miscarriage
False negatives can be caused by:
- taking pregnancy tests too soon. The best time to test is after your first missed period or fourteen days after suspected conception has occurred.
- taking a pregnancy test using anything but the first morning's urine. You need to allow the hCG to become concentrated in your urine. The longer you go without urinating, the more hCG there will be in the urine. If you use urine from any other time of day, you should try not to urinate for several hours to allow the hCG to build up. But, again, the first morning urine is the most potent.
- using the wrong pregnancy test. Pregnancy tests check for different levels of hCG in the urine. One test may require as little as 10 mIU of hCG to produce a positive test result, such as hCG One Step Ultra. While another may require 50mIU of hCG such as the e.p.t. Certainty Digital. (http://www.fertilityplus.org/faq/hpt.html
)
- not following the timing directions properly. It is important that you follow the directions to the letter and only check the test when the required amount of time has passed. If you check it too early, you may wrongly interpret the test results before the line has time to appear.
- not urinating long enough on the stick or immersing the stick in the urine for long enough.
- using a pregnancy test that is past its expiration date.
- certain medications or medical conditions.
Quick fact about pregnancy tests:
-birth control pills do not contain hCG. So birth control pills will not cause a false positive pregnancy test result.
