Home Pregnancy Tests: What Affects The Test

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What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Taking the test very early in your pregnancy. HCG may not be found. In this case, the test kit may show that you are not pregnant when you really are pregnant. This is called a false-negative result. If you have drunk a lot of fluid, your urine may be diluted and this may also cause a false-negative result.
• Having soap in the urine collection cup. This may cause the test results to show that you are pregnant when you are not pregnant. This is called a false-positive result. False-positive results may also be caused by reading the test at the wrong time, letting the test equipment get warm, having protein or blood in the urine, or having hCG hormone in the urine from some other cause.
• Taking certain medicines, such as chlorpromazine hydrochloride and methadone hydrochloride (Dolophine, Methadose).
• Taking fertility medicines that contain human chorionic gonadotropin.
• Not reading the result at the right time as shown on the instructions. If you read the result too early or too late, the color change may not be accurate and you will need to retest.

Last updated:	July 15, 2008
Author:	Sandy Jocoy, RN
Reviewed By:	Joy Melnikow, MD, MPH - Family Medicine, Deborah A. Penava, BA, MD, FRCSC, MPH - Obstetrics and Gynecology
Editors:	Kathleen M. Ariss, MS, Tracy Landauer