An hCG (human chorionic gonadotropin) urine test is a pregnancy test. The hCG hormone, also called the pregnancy hormone, is produced in the placenta of a pregnant woman. If you are pregnant, this hormone can usually be detected in your urine about 10 days after your first missed period. This is when the fertilized egg becomes attached to the uterine wall.
During the first 8 to 10 weeks of a normal pregnancy, hCG levels increase very rapidly. These levels reach their peak at about the 10th week of pregnancy, and then gradually decline until delivery.
HCG urine tests are commonly sold in kits that you can perform at home, so the hCG urine test often is referred to as a home pregnancy test.
The hCG urine test is used to confirm pregnancy about one to two weeks after a missed period. This is a qualitative test, which means that it will tell you whether or not the hCG hormone is detected in your urine. It is not intended to reveal specific levels of the hormone. The presence of hCG in your urine is a considered a positive sign of pregnancy.
An hCG urine test can be performed at your doctor’s office or at home with a home pregnancy test. Both will require the collection of a urine sample. An hCG urine test conducted at home is similar to the test that your physician conducts. Both have the same ability to detect hCG in your urine.
Most hCG urine tests sold for home testing use follow a similar procedure for accurate testing. While you should carefully follow the instructions included with your kit, the process typically follows these steps:
- Wait one to two weeks after your first missed period to get the most accurate results. Note: Irregular periods or miscalculations of when a period is due can affect your test. In fact, 10 to 20 percent of pregnant women may not detect their pregnancy by testing on what they believe to be the first day of their first missed period, according to the FDA.
- Plan to use the test the first time you urinate after waking up. As this urine is the most concentrated, it will contain the highest hCG levels of the day. Your urine will become more diluted as you drink liquids, so hCG levels may be harder to measure later in the day.
- For some home pregnancy tests, you will hold an indicator stick directly in the urine stream until it is soaked (for about five seconds). Other kits require that you collect urine in a cup and then dip the indicator stick into the cup to measure if the hCG hormone is present.
- Home hCG urine tests usually include an indicator that shows whether the test is being properly performed. For example, it will indicate if there is enough urine on the stick to get an accurate result. If the control indicator doesn’t activate during your test, the results may be inaccurate.
- For most tests, it takes only about 5 to 10 minutes for a result to appear. Typically, a colored line or plus symbol will appear on the test stick to indicate a positive result. The absence of a colored line or a negative sign usually indicates a negative result.
The only risks associated with an hCG urine test involve obtaining a false positive or false negative result. A false positive result would indicate pregnancy, even though there is none. Rarely, the test may detect abnormal, non-pregnancy tissue and needs follow up by your doctor. These results are rare, as the hCG hormone is usually only produced by pregnant women.
There is a higher risk of obtaining a false negative result. If you obtain a false negative result, in which case the test says you are not pregnant but you really are, you might not take the precautions necessary to give your unborn baby the best possible start. Such results may occur more commonly in early pregnancy or if the urine is too diluted to detect hCG.
There are no special preparations necessary to take an hCG urine test. You can ensure the most accurate results with simple planning.
If you are taking a home test:
- carefully read the instructions included in your test kit before collecting your urine sample
- make sure the test has not passed its expiration date
- look for the manufacturer’s toll-free number on the package and call it if you have any questions about using the test
- arrange to use your first morning urine one to two weeks after your first missed period
- do not drink large amounts of fluid before collecting your urine sample—drinking liquids may dilute hCG levels and make them difficult to recognize
Discuss any medications you are taking with your pharmacist or physician to determine whether they could affect the results of an hCG urine test.
Diuretics and an antihistamine called promethazine can cause false negative results, which would not recognize that a pregnancy exists.
False positive results, which would indicate you are pregnant when you’re not, can be caused by anti-convulsants, anti-Parkinson drugs, hypnotics, and tranquilizers.
The accuracy of your hCG urine test results will depend on your ability to closely follow the test kit’s instructions. If you have a negative result, you should consider these results to be uncertain, as they may indicate a false negative. Until you can be sure that you are not pregnant, you should be cautious and avoid doing anything that could hurt a developing fetus. Smoking, using alcohol and certain medications can harm your baby in early pregnancy.
A false negative result can be caused by:
- using a urine sample collected after your first morning urine
- taking the test before there is enough hCG to produce a positive result
- miscalculating the timing of your missed period
If you have a negative result, you should repeat the test in about a week to confirm the absence of pregnancy. If you believe the tests are indicating a false negative, and that you are pregnant, you should consult your physician. He or she can conduct an hCG blood test, which is more sensitive to lower levels of the hCG hormone than the hCG urine test.
If you have a positive result, it means that the test detected hCG in your urine. Your next step should be to consult your physician. He or she can confirm pregnancy with an exam and additional testing, if necessary. By getting prenatal care early in your pregnancy, you will give your baby the best chance for healthy growth and development before and after birth.