What causes a negitive pregnancy test to become positive after the alotted time?
449015
A standard pregnancy test detects the amount of a hormone called HCG (human chorionic gonadotropin), which is present in greatly elevated levels in the urine (or blood) during early pregnancy. This elevated level may not be high enough to be detected in a given sample, and it increases over the first weeks of a pregnancy so if it's not positive the first time, it may be a few days later.
765182
maybe your hcg levels are high because your further along than expected... and it might be possible for them to spike.. also maybe the test was just very sensitive... Good Luck and Lots of baby dust ++++++++++++++++++\n\nTracy
953052
You need to make an appointment with your doctor. I experienced similar symptoms and had a negative pregnancy test and it turned out that I was pregnant.
233569
Usually they say to wait and see if you miss a period, but I knew before mine was even due when I was pregnant with my daughter. A test came back positive three weeks after she was conceived. If you think you may be pregnant, if you had unprotected sex, wait a couple of weeks and then take a test.. although sometimes the urine tests don't show up, a blood test is the best way to tell if you're pregnant, if it's very early on.
787039
I think if you want a positive answer you should go to your doctor and ask for the blood test to see if you are actually pregnant. Pregnancy tests aren't always 100%.
451122
Yes, it is possible to be pregnant and have a negative home pregnancy test.  The test works by detecting HCG in your urine that you produce when you are pregnant.  You CAN be pregnant and not have enough HCG to turn one positive.  If you really want to know, go to your doctor and ask for a Beta Quantitative Analysis, which is the definitive blood test for pregnancy.
258232
Although home pregnancy tests are pretty accurate, I would suggest calling your obgyn dr. - ESPECIALLY if you are on any form of birth control pills.  It could be from excessive stress, excessive changes in your physical activity or eating - but it would be good to at least let your dr. know what's going on.
465636
false pregnancy. you may have the symptoms  of pregnancy and very confident that you are pregnant but you are not
550343
I would be confused, too.  When I was pregnant my first several tests were negative because there wasn't enough hormone in my pee.  I was drinking lots of water and I wasn't testing in the morning.  Make sure your pee is concentrated enough to get an accurate test.
636221
Some pregnancy test manufacturers claim you do the test the day after your period is due. The longer you wait, the more likely it is to be accurate - you're less likely to get a false negative result, because the concentration of the pregnancy hormones will be greater. The best time to do a test is first thing in the morning, because your urine is more concentrated in the morning.
497515
My friend was almost 5 months pregnant before she got a positive pregnancy test. Her periods had not been regular since getting off the depo shot. She thought she was pregnant..but all the tests said negative. Eventually she got a positive test...but even at 5 months the line was very light. The dr. couldnt explain why the tests came out negative. But her son is perfectly healthy..and thats all that matters!
232625
False -'s are far more common than false +'s. If you are pregnant, you might have tested too soon so the hormone wouldn't be as prevalent. Or it could be simply human error. If you still suspect you are pregnant, make an appointment with a doctor. They are the only one's who can tell you for sure.
345546
Let the doctor know.  I means you get another test. This happens frequently.
898959
Not all home test kits are accurate.  I took one after knew I was pregnant (done at a doctors office) and it said negative. The only true way to know for sure is through a blood serum test.  You show the classic symptoms of pregnancy, and I am pretty sure thats what you will find out tomorrow.
32862
Sometimes pregnancy tests will not show up positive (even if you are pregnant) if you take it too soon after you got pregnant.  If I were you, I would wait at least 7 to 10 days after the last time you had sex and take another test.  Generally, drinking a lot of water would NOT affect the results of your pregnancy test.
277417
There are a number of things that could cause that.  If there was a possibility that you were pregnant it may be a sign that you had a miscarriage. (You should see a doctor.)  Certain skin allergies can cause the same response, too. (You should see a doctor.)
992629
The morning after pill can affect the date of your next period. It is recommended that a pregnancy test be done if you have not had your period within 21 days.\n\nAs you have already done this it is doubtful that you are pregnant, pregnancy test are fairly accurate.\n\nIt is possible that your problem is due to starting BC 2 days after the incident. It is generally recommended that you start BC after your next period. It is also possible that stress and worry are a factor as suggested in a previous answer.\n\nI would suggest you wait a further week, if still nothing take a further pregnancy test and if still negative check with your doctor.