Home pregnancy tests can find the presence of a pregnancy hormone (called human chorionic gonadotropin, or hCG) in a sample of urine. High levels of hCG are made during pregnancy. The home tests have similar results to the pregnancy tests done on urine in most doctors' offices if they are used exactly as instructed.
When a woman becomes pregnant, the egg is generally fertilized by a sperm cell in a fallopian tube (conception). Within 9 days after fertilization, the egg moves down the fallopian tube into the uterus and attaches (implants) to the wall of the uterus. When the fertilized egg implants, the placenta starts to develop and begins to release hCG into the woman's blood. Some of this hCG also passes in her urine. In the first few weeks of pregnancy, the amount of hCG in the urine gets higher very quickly—it doubles every 2 to 3 days.
There are two basic types of home pregnancy tests.
The first urine of the morning (that has collected in the bladder overnight) is the best one to use and has the most accurate test results.
The accuracy of home pregnancy tests is different for every woman because:
While a few home pregnancy tests may be sensitive enough to show a pregnancy on the first day of a woman's missed period, most test kits are more accurate about a week after a missed period.
A home pregnancy test is done to detect pregnancy by detecting human chorionic gonadotropin (hCG) in your urine.
You can buy home pregnancy test kits at the drugstore or grocery store. You don't need a prescription.
The test kits generally have plastic dipsticks or test strips and instructions that explain how to do the test. Some kits have a urine collection cup and a dipstick that you dip in urine. Midstream kits have a test strip that you hold in your stream of urine for several seconds. All kits tell you to wait a specific amount of time before reading the results.
Home pregnancy kits can be used on the first day of a missed menstrual period. But the test results are more accurate if you wait a few days longer. If you do the test as soon as you have missed a period and the results show you are not pregnant (negative results), repeat the test in 1 week if your menstrual period has not started, or have a pregnancy test done at your doctor's office or a clinic.
For any home test, you should follow some general guidelines:
Carefully read the instructions that come with the home kit. Instructions vary from kit to kit. Be sure to read the result at the appropriate time indicated in the instructions for accurate results.
If you have a kit that asks for a morning urine sample, test urine that has been in the bladder for at least 4 hours. A first morning urine sample (that has collected in the bladder overnight) gives the most accurate test results. Test the urine within 15 minutes of collecting the sample.
If you are using a midstream kit, urinate a small amount first and then hold the dipstick in your urine stream as you finish urinating. Test the urine sample according to the directions included in the test kit package.
There is no pain or discomfort in doing a home pregnancy test.
There are no problems with collecting a urine sample for a home pregnancy test. But there may be a chance that you read the results wrong. With any home pregnancy test, if the test shows you are pregnant (positive test), you should see your health professional to confirm the test and arrange follow-up care. If the test does not show you are pregnant (negative test), it is still possible that you may actually be pregnant. You should repeat the test in 1 week if your menstrual period has not started. If the repeat test is negative, probably you are not pregnant, but you should talk to your health professional about why you are not having periods.
Home pregnancy tests can find the presence of a pregnancy hormone (called human chorionic gonadotropin, or hCG) in a sample of urine. If you are pregnant, most tests show a color change or a symbol shows in the indicator area of the test strip or on the part of the test device.
Reasons you may not be able to have the test or why the results may not be helpful include:
Other Works Consulted
- Fischbach FT, Dunning MB III, eds. (2009). Manual of Laboratory and Diagnostic Tests, 8th ed. Philadelphia: Lippincott Williams and Wilkins.
- Pagana KD, Pagana TJ (2010). Mosby’s Manual of Diagnostic and Laboratory Tests, 4th ed. St. Louis: Mosby Elsevier.
|Primary Medical Reviewer||Sarah Marshall, MD - Family Medicine|
|Specialist Medical Reviewer||Siobhan M. Dolan, MD, MPH - Reproductive Genetics|
|Last Revised||April 4, 2012|
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