A pregnancy test may let you know, one way or the other, if you are pregnant.
What is a pregnancy test and how does it work?
A home pregnancy test detects the presence of the pregnancy hormone, human chorionic gonadotrophin (hCG), in your urine. This usually happens — but not always — about six days after fertilization. If you’re pregnant, levels of hCG continue to rise rapidly, doubling every two to three days.
When should you take the home pregnancy test?
- Most tests can tell whether you’re pregnant on the first day of your missed period.
- Usually you can take the test at any time of day. When you decide to test, try not to drink too much beforehand, as it could dilute the levels of hCG in your urine.
- Some tests may recommend that you use the first urine of the day, particularly when testing early. Levels of hCG become more concentrated in your urine overnight.
- If you have irregular periods, it may be harder to calculate when your period is due. Allow for your longest cycle in recent months before testing.
- If you have recently stopped taking the pill, you may not know how long your natural cycle is, and may end up testing either too soon or too late. If your test is negative, you should test again in three days.
What types of pregnancy tests are available?
Two main types of pregnancy tests can let you know if you’re pregnant: urine tests and blood tests.
Urine tests can be done at home or in a pathology laboratory. Many women first choose a home pregnancy test to take about a week after a missed period. Home pregnancy tests are private and convenient.
Follow the test instructions completely for the most accurate results. After testing, you can confirm results by seeing your doctor.
Blood tests are used less often than urine tests. These tests can detect pregnancy earlier than a home pregnancy test, or about six to eight days after ovulation. But with these tests, it takes longer to get the results than with a home pregnancy test.
Blood tests (also called a beta hCG test) measures the exact amount of hCG in your blood. It can find even very low levels of hCG. Because these pregnancy tests can measure the concentration of hCG, they may be helpful in tracking any problems during pregnancy. They may also be used to rule out a tubal (ectopic) pregnancy or to monitor a woman after a miscarriage when hCG levels fall rapidly.
How accurate are these urine and blood pregnancy tests?
Waiting for at least a week after a missed period may give you the most accurate result. Results may also be more accurate if you do the test first thing in the morning, when your urine is more concentrated.
Urine home pregnancy tests are about 97% accurate. Blood tests are even more accurate than this.
How accurate a home pregnancy test is depends upon:
- How closely you follow instructions.
- When you ovulate in your cycle and how soon implantation occurs.
- How soon after pregnancy you take the test.
- The sensitivity of the pregnancy test.
You may take a blood test to get a better idea of what is happening in very early pregnancy (before an ultrasound can pick up on a pregnancy). It can help detect an ectopic or molar pregnancy. It’s a good way to detect that the level of hCG is rising in a way expected for a healthy pregnancy.
Where can I buy a pregnancy test?
You can buy pregnancy tests, without prescription, at most chemist shops and some supermarkets. You can also buy them online.
How early can you take a pregnancy test?
It is safe to assume that most (but not all) newly pregnant women will have a sufficient amount of hCG by 7 to 10 days post ovulation to confirm pregnancy with a highly sensitive home pregnancy (for example, a test calibrated to detect 20 mIU/ml of hCG).
It is important to note, however, that testing this early can result in a false negative, especially if you ovulated later than you thought, your hCG production is on the low end of normal, or if implantation has not occurred yet.
If you decide to test as early as 7 days post ovulation and you get a negative result, it is recommended to take the test again in a few days, just to be sure! Therefore, the simple answer to the “how early can you take a pregnancy test” question is between 7 and 10 days after ovulation. Definitely much better than waiting a full two weeks!