Home Pregnancy Tests
chorionic gonadotropin, or
hCG for short, is produced by the
placenta of the implanting
embryo. hCG is
commonly known as "the pregnancy hormone".
Home pregnancy tests have substances in them that
will combine with the HCG in your
urine to form a visible
line or plus sign
if the level of HCG in your urine
is high enough
for the test to detect. It usually takes about 10 days after conception
before hCG can be detected by a home pregnancy test in your urine. A few tests
are able to find hCG at very low levels in your urine, and can detect up to 97% of pregnancies on the day of a missed
For all pregnancy tests, follow the directions exactly. Test your urine first thing in the morning, when your urine is most
concentrated. The tests usually take about 5 to 10 minutes to detect hCG.
Most home pregnancy tests are performed by
dipping the test strip into a sample of your urine or by urinating directly on
the test strip. The pregnancy test has a "control band" to
let you know the test has been done correctly. If there has been enough urine
absorbed by the test strip and the test is working properly, a line should appear in the control
area of the test .
If no control band appears at all, you
most likely did not apply enough urine to the
test strip, and you will need to repeat the test .
problem occurs again, there may be technical problems with the test, and
stop using the test kit
and contact your local distributor.
one to ten minutes if the amount of hCG in your urine is high enough to be detected by your
line will appear on the test in addition to the control line .
tests, the lines will overlap to form a plus sign.
All results should be confirmed by your healthcare provider, especially when
decisions about future medical care.
Result: Negative Pregnancy Test
Only a control band appears .
This means the amount of hCG is less than the pregnancy test is able to
Is it possible the test could be wrong?
Yes. False negative pregnancy test results can occur.
A false negative pregnancy test is a test result that says you're not
pregnant when you really are pregnant. Some possible reasons for a false
negative pregnancy test include:
You did not wait long enough for the substances in the test to combine with the hCG in your urine. Repeat the test and wait ten minutes.
You took the test too soon. Wait 3 to 7 days and repeat the test.
Your urine is too dilute. Drinking too much fluid before taking a home pregnancy test
waters down the level of the hCG in your urine making the amount of hCG too low
for some tests to detect. Retest your urine first thing in the morning
before you drink any fluids.
A very high hCG level (or one of hCG's forms) in your urine is preventing the
substances in the test from combining properly. This is known as the hook
effect. This is most likely to occur after 5 weeks of pregnancy. Add water to
your urine sample to lower the level of hCG in your
urine and retest your urine.
If you have missed a menstrual period and have lower abdominal pain, call your
health professional immediately even if the pregnancy test is negative. You
could have an ectopic pregnancy (a
pregnancy implanted outside of the uterus) which can be life threatening
Result: Positive Pregnancy Test
A control band and a second line or a plus
sign appears. *
The test has detected the presence of hCG.
Is it possible the test could be wrong?
Yes. False positive pregnancy test results can occur, but they are much less
common than false negative pregnancy tests.
A false positive pregnancy test is a test result that says you're pregnant
but you really are not pregnant.. Some possible reasons for a false positive
pregnancy test include:
You have had a pregnancy termination or miscarriage within the last 5 to 6 weeks.
You have been taking medications that contain hCG (such as Pregnyl, Profasi, Pergonal, A.P.L.).
The test is defective.
hCG is being produced by a source other than normal placenta such as:
Trophoblastic disease, breast cancer, lung cancer,
The pituitary gland in postmenopausal women
*If a control band and a faint second line or a plus sign appears
you could be pregnant. Wait a few days and retest your urine or go to ask to
see your health care provider
1. Cole LA.The utility of six over-the-counter (home) pregnancy tests.Clin
Chem Lab Med. 2011 Aug;49(8):1317-22.PMID:21812725
Davison CM, et al., Qualitative beta-hCG urine assays may be misleading in the
presence of molar pregnancy: a case report.
J Emerg Med. 2004 Jul;27(1):43-7. PMID:15219303
3. Gronowski AM, et al., False-negative
results in point-of-care qualitative human chorionic gonadotropin (hCG) devices
due to excess hCGbeta core fragment.
Clin Chem. 2009 Jul;55(7):1389-94. PMID:19395437
4. Grynberg M, et. al., Rupture of ectopic
pregnancy with negative serum beta-hCG leading to hemorrhagic shock.
Obstet Gynecol. 2009 Feb;113(2 Pt 2):537-9. doi:
Er TK, et. al., False-positive urine pregnancy test in a woman with adenomysosis.
Am J Emerg Med. 2009 Oct;27(8):1019.e5-7. doi: 10.1016/j.ajem.2008.12.023. Epub
2009 Sep 22.
Maughan BC, Kamat A.Lung carcinoma presenting with pathologic femur fracture and false-positive
pregnancy test result.Ann Emerg Med. 2012 Sep;60(3):378-80. PMID:22424649
7.Levsky ME, Handler JA, Suarez RD, Esrig ET. False-positive urine beta-HCG in a woman with a tubo-ovarian abscess. J Emerg Med. 2001;21:407–409.PMID:11728769
8.Cole LA, et. al.,
Accuracy of home pregnancy tests at the time of missed menses. Am J Obstet Gynecol. 2004 Jan;190(1):100-5.PMID:14749643