First of all, it is very important to know that 20% of all pregnancies do end in miscarriage. That is a huge number, and a very sad fact. Of course, with something such as miscarriage, there are no “rules,” no “facts” and no guidelines to go by. These numbers are just estimates and there are no guarantees. However, it is said that the risk of miscarriage is greatest in the first and second weeks of pregnancy, when you are not likely to even know that you are pregnant. This is called an early or chemical miscarriage, and can be the reason for the ‘false positive‘ you are seeing on your pregnancy test.
The chances of miscarriage continue to drop after those first initial weeks, though. After the first two weeks, the chances of miscarriage drop to ten percent. During weeks six through twelve of your pregnancy, the chance of miscarriage drops to only five percent. During the second trimester of your pregnancy, the chance of miscarriage drops once again to only three percent. Of course, none of these numbers are set in stone, just a basic rough estimate for you to go by. That is why so many women wait until 12-13 weeks when they enter the second trimester to share their good news with the world, as their chances of miscarriage or pregnancy loss drop so precipitously at this time. Once this far along, most couples feel pretty certain in their pregnancy at this time.