Why negative pregnancy test then it was positive?

There are a few reasons why you might get a negative pregnancy test followed by a positive pregnancy test.

* Early pregnancy. If you take a pregnancy test too early after conception, the level of human chorionic gonadotropin (hCG) in your urine may be too low to be detected. hCG is the hormone that pregnancy tests detect. As your pregnancy progresses, the level of hCG in your urine will increase, making it more likely that a pregnancy test will be positive.

* Implantation bleeding. Some women experience implantation bleeding around the time of their period. Implantation bleeding is light bleeding or spotting that occurs when the fertilized egg implants in the lining of the uterus. Implantation bleeding can be mistaken for a period, and it can lead to a negative pregnancy test if you take the test too soon after implantation.

* Miscarriage. A miscarriage is the loss of a pregnancy before 20 weeks. If you have a miscarriage, the level of hCG in your urine will drop, and you may get a negative pregnancy test.

* Ectopic pregnancy. An ectopic pregnancy is a pregnancy that occurs outside the uterus. Ectopic pregnancies can be dangerous, and they can lead to a negative pregnancy test if the hCG level in your urine is not high enough to be detected.

If you get a negative pregnancy test but you think you might be pregnant, it's important to talk to your doctor. Your doctor can order a blood test to check your hCG level and determine if you are pregnant.