Do not worry. Some amount of spotting during your second trimester is common condition, due to cervical growth or inflammation, that could cause bleeding in the second half of pregnancy. The most common cause of heavy vaginal bleeding in the later parts of pregnancy is a problem with the placenta. So if you experience any type of bleeding or spotting, you need to contact your doctor. He/she will try to determine the reasons for the bleeding. If you use pads to soak up the blood, keep track of how many you have used. All this information can help your doctor to decide if your spotting or bleeding is a normal part of pregnancy or something more serious. All the best and take care.