While bleeding and spotting is pretty normal for the first trimester it is not normal for the second trimester. There are some situations, however, where bleeding or spotting during the second trimester may be perfectly normal.
For example, if the bleeding or spotting occurs right after, or within 24 hours, of having sexual intercourse then more than likely these spotting ids related to some small capillaries in the cervix breaking. As long as the bleeding is light and resolves within a day there is probably no need to worry. Of course, if you have any concerns you should take them up with your care provider because during the second trimester the sooner a problem is dealt with the more likely the pregnancy is to continue. If you have heavy bleeding that is bright red, regardless of whether you recently had sex or not, then you should visit your doctor immediately.
Another reason for bleeding during the second trimester is a vaginal exam. Not all women will bleed immediately after the exam, but it could occur later in the evening or even the next day. As long as the bleeding is light and brown colored there is not much cause for concern. If the bleeding is heavier and more like a period then you should contact your doctor right way.
Heavy bleeding that does not taper off could be nothing at all or it could be a sign of a late miscarriage or preterm labor. Do not wait to determine what the cause is or if the bleeding will stop on its own if it is heavy. Ever second counts and the sooner you get to your doctors the more likely they will be able to help you.
Most women do not experience bleeding or spotting during the second trimester, although some do. For some of these lades there is nothing amiss with the pregnancy and the bleeding may be explained or unexplained. On the other hand there could be a serious problem that needs immediate medical treatment. Always call your doctor if you are worried about spotting or bleeding in the second trimester.