I took morning after pill started my period July 14th it lasted 4 days when usually its 7 now is Aug 15 and i still havent started. a pregnancy test tht showed negative can be pregnant?

It is possible for a pregnancy test to show a negative result even if you are pregnant. This is known as a false negative. False negatives can occur for a number of reasons, including:

* Testing too early. Pregnancy tests work by detecting the presence of human chorionic gonadotropin (hCG) in your urine or blood. hCG is a hormone that is produced by the placenta after implantation of a fertilized egg. However, it can take several days for hCG levels to build up to detectable levels. If you test too early, you may not have enough hCG in your system to produce a positive result, even if you are pregnant.

* Using an expired or defective test. Expired or defective pregnancy tests can give false negative results. Always check the expiration date on your pregnancy test before using it and make sure that the test is not damaged.

* Incorrectly using the test. If you do not follow the instructions on the pregnancy test package carefully, you may get a false negative result. This includes not waiting the full amount of time for the test to develop or not collecting urine correctly.

If you think you might be pregnant, even if you have a negative pregnancy test, you should see your doctor to confirm. Your doctor can order a blood test to measure hCG levels and perform an ultrasound to see if there is a developing pregnancy.