I've see a few post on this. Here's some info that I found.
A repeatedly negative pregnancy test when you missed your period means that you are not pregnant and after a week of a missed period with negative pregnancy tests your chance being pregnant is 1%. The timing of a positive pregnancy test depends on implantation. If you are pregnant then a urine pregnancy test is not expected to be positive until at the very earliest 3-4 days after implantation, which is about 10 dpo days after ovulation/fertilization (4 days before the next period), and about 51% of pregnant women have a positive pregnancy test 2 days before the expected next period. What are your chances of still being pregnant when you are trying to conceive and have a negative pregnancy test? What are your chances getting a positive HPT if you are pregnant? Below is a table showing your chances of still being pregnant with a negative pregnancy test on different days of your menstrual cycle: Pregnancy Chances after a Negative Pregnancy Test in Relationship to Ovulation and the Days before or after the Expected PeriodDays Post Ovulation (DPO)Day of Expected Period (EP)Chance of Still Being Pregnant with a Negative HPTChance of NOT Being Pregnant with a Negative HPT% of Pregnant Women with a positive Pregnancy Test12 DPOEP -312.3%87.8%51%13 DPOEP -29.5%90.5%62%14 DPOEP -18.0%92.0%68%15 DPOExpected period6.5%93.5%74%16 DPOEP +15.3%94.8%79%17 DPOEP +23.8%96.3%85%18 DPOEP +32.5%97.5%90%23 DPOEP +71%99.0%96%Date are based on the fact that in each menstrual cycle there is an about 25% chance of getting pregnant as well as a scientific study published by Wilcox in JAMA in 2001. Your chance of getting pregnant each month may be different depending on your age, certain medical issues, whether you ovulate or not, and if your are trying to get pregnant with IVF or other fertility medications. Besides being pregnant, the next reason for missing your period is not ovulating (anovulation). That's why it's essential for every woman who TTC to chart her fertility and to know precisely each cycle if ovulation happened or not. Knowing if and when you ovulated usually removes any confusion you may have if your period didn't come. Start charting your fertility NOW. It helps you find out if you ovulated, whether you are fertile, and it will let you know early on if you are pregnant. If you know you ovulated and your period hasn't come 15+ DPO, then there could be only one reason: You are pregnant. If you know that you did not ovulate then you can often expect your period not to come and you are prepared for that. View Thread
Home Pregnancy TestsHuman Chorionic Gonadotropin (hCG) pregnancy tests or home pregnancy tests determine pregnancy through the detection of the hormone Human Chorionic Gonadotropin (hCG) in a woman's urine. Doctors recommend that you wait until you have missed a period to take a home pregnancy test. If you can not wait that long to find out and you know the day you may have conceived, then the earliest you can take a test would be 14 days from possible conception. Home tests are usually 97% accurate when all instructions are followed correctly and the results are read on time. Some kits come with two tests so that in case you have made a mistake, you may take the home pregnancy tests gain. Learn more about the accuracy of home pregnancy tests in another relevant article. False Negative hCG Pregnancy Tests And What Causes ThemIf you take a home pregnancy test too early, you may get a false negative result. A false negative result is when the test says you are not pregnant but you are. This can be misleading and when using home pregnancy tests you must be very careful of avoiding any factors that may cause false results. The major reason for a false negative test is that you took the test too early. Pregnancy tests vary in their sensitivity which means how soon they can detect the hormone Human Chorionic Gonadotropin (hCG) in your urine. It is possible that although your ovum might be fertilized, meaning you may be pregnant, but your body has not started secreting enough Human Chorionic Gonadotropin (hCG) for the test to measure. Your body needs time for the hormone to rise to a high enough level to be detected in a test. If the home pregnancy test shows negative results but you still think you could be pregnant, wait a few days and try again. A negative result can mean that you are not pregnant, you took the test too early or you took the test wrong. Also, if you have received different answers on multiple pregnancy tests, it is recommended that you get a blood test done to get an accurate answer.
For most pregnant women the urine pregnancy test does not detect enough hCG until 1-2 days before missing the period. And in 1 of 4 pregnant women the home urine pregnancy test does not become positive until after they miss their period. Most false negative pregnancy tests occur when testing is done too early. You are pregnant but you test negative because there is not enough of the pregnancy hormone hCG in your body and especially your urine to be detected. Check your chances of being pregnant or not with a negative pregnancy test HERE. Quantitative blood tests and the most sensitive urine tests usually detect hCG shortly after implantation, which can occur anywhere from 6 to 12 days after ovulation. Beta hCG levels rise exponentially in the first two months or so of pregnancy so the earlier the test is performed, the higher the chance of a false negative result. Less sensitive urine tests and qualitative blood tests may not detect pregnancy until three or four days after implantation. Menstruation occurs on average 14 days after ovulation, so the likelihood of a false negative is low once a menstrual period is late. View Thread
I bet some of you are wonder why you should always use 1st morning urine when testing with home tests.
Well the theory is that because most women sleep 8 hrs a night and that means that your urine collects over that amount of time and has time to condense/build up. So using that condensed urine give you a better chance of accurate results.
Now this hinges on also when you are testing. I don't suggest testing until you are at least 3-5 days late. That way if you are indeed pregnant that should give the pregnancy hormone in your urine to reach levels that most test should be able to pick up.