why do some pregnancy tests show negative

The accuracy of a depends on how and when you take the test, so it's possible that your negative pregnancy test result is not be accurate. What's a false negative pregnancy test result? A "false negative" pregnancy test result shows that you're not pregnant when you are. Why do false negative pregnancy test results happen? The test was taken too soon. If you take a very soon after you think you may have, or if you didn't follow the test instructions correctly, you might get a false negative test result. A home pregnancy test will be positive only if it detects the pregnancy hormone human chorionic gonadotropin (hCG).

When an egg is fertilized after you, it takes about a week to travel through a fallopian tube to the uterus. And your body starts producing hCG only after a fertilized egg. If it's very early in your pregnancy, your body might not have produced enough hCG yet. In that case, you'd get a negative result at first. Also, some tests are more sensitive than others, and no test is 100 percent accurate. And a few women have such low levels of hCG during pregnancy that home tests can't measure it. Although some tests can detect hCG the first day you miss your period, you'll have a better chance of getting an accurate result if you wait a week.

Don't time the test based on when you think you might have conceived. Sperm can live in the fallopian tubes for up to five days, so it's possible you conceived several days after having sex. Hormones were low. For the most accurate result, follow the test instructions exactly, and take the test when you first get up in the morning. That's the time when your urine and any hCG is the most concentrated. What if the test is taken correctly and I get a negative result?

If you're sure you've waited long enough to test and you're, you're probably not pregnant. Pregnancy isn't the only reason for a missed period stress, too much exercise, and thyroid problems, among other things, can all delay menstruation. If your period is weeks late without a positive test result, talk to your doctor to figure out whether you're pregnant or need help getting your menstrual cycle on track. Learn more: Join our group discussion.
If you're trying to get pregnant, there's good news: You may still be pregnant. Sometimes, levels of the pregnancy hormone human chorionic gonadotropin (hCG) early in pregnancy arenвt yet high enough for a home pregnancy test to detect.

One study found that home pregnancy tests only have to be capable of detecting hCG levels above 25 mIU/mil to achieve the commonly advertised 99 percent accuracy rate. Another study calculated that in order to detect 95 percent of pregnancies, a test would have to be able to detect levels as low as 12. 4 mIU/ml. But not all home pregnancy tests were consistently sensitive enough to do so. A woman's cycle can vary widely, so if you happened to conceive later in your cycle, your hormone levels may not be high enough.

Pregnancy bleeding, recent hormonal contraceptive use, or breast-feeding can all interfere with a woman accurately knowing her dates. There can be as much as 13 days difference to when ovulation occurs, meaning that you may think you are 4 weeks pregnant when you're only two weeks along. If you think you may be pregnant and missed a period, but are getting a negative result on your pregnancy test, wait a few days, then retest. If you continue to miss your period, be sure to talk to your doctor to rule out any complications.