- There are two main types of pregnancy tests: blood and urine tests.
- Blood tests are more sensitive and can tell you if you’re anywhere from 6 to 14 days after conception.
- Most home pregnancy tests advise you to take the test after you miss your next period, which could be anywhere from 14 to 18 days after conception, depending on when in your cycle you conceived.
- This article was reviewed by Karen Duncan, MD, who is an assistant professor with the Department of Obstetrics and Gynecology at NYU Langone.
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You have two options when it comes time to see if you have a baby on board.
The most common is an at-home urine pregnancy test, available over the counter, though you can take a urine pregnancy test at a medical clinic. Another option is a blood test performed at a medical clinic.
“Both tests check for a hormone called human chorionic gonadotropin, or hCG,” says Crystal Newby, MD, of Kansas City Ob-Gyn. “This hormone is produced after a fertilised egg attaches to the wall of your uterus.”
The egg typically attaches 6 days after fertilisation, at which point, hCG levels in your blood and urine will increase for the next 6 to 10 weeks. Once hCG levels are high enough, you can expect an accurate reading, but not before then.
Blood pregnancy tests (6-14 days)
Blood tests for pregnancy are more sensitive to hCG than home pregnancy tests. They can detect this hormone in low quantities and tell you if you’re pregnant sooner than a home test.
Depending on a woman’s cycle, a blood test can detect pregnancy between 6 and 14 days after conception and is considered by doctors to be 99% accurate.
While blood tests can provide results sooner than home pregnancy tests, they are usually more expensive and take longer to provide results because the blood must be sent to a lab for analysis.
If the lab is in-house then it will take a few hours. But if the lab is at a different location, it could take several days to learn the results.
Home pregnancy tests (14-18 days)
Home pregnancy tests can provide results faster and be more convenient than a blood test. But you’ll probably have to wait longer to receive accurate results.
Most home pregnancy tests advise you to take the test after you miss your next period. If you have a standard 28-day cycle, you’ll be most fertile two to three weeks before your period. So if you get pregnant during that fertility window, you’ll need to wait at least 14 to 18 days after conception to take a home pregnancy test.
If you follow directions, home pregnancy tests are an estimated 97% to 99% accurate. Yet if you get a negative result and suspect you’re pregnant, check the instructions on the box. Home pregnancy tests typically recommend retaking the test 5 to 7 days later, when the hCG levels in your body will be higher.
This type of result is called a “false negative.” Sometimes you can receive a false negative result if you take a pregnancy test too soon when your hCG levels are too low for the test to detect them accurately.
Moreover, recent miscarriages, fertility drugs, and rare hCG secreting tumours can interfere with the results of at-home urine tests. If you receive conflicting results after taking a home pregnancy test multiple times, doctors recommend a blood test.
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