If you are experiencing bleeding or spotting at 16 DPO, the chances are it could be implantation bleeding. Slight bleeding or spotting because of implantation (when a fertilised egg attaches to the uterine wall) is fairly common in early pregnancy and is one of the first signs of pregnancy. So, do not worry if you are seeing slight spotting at 16 DPO. However, do note that implantation bleeding is on a lighter side as compared to menstrual bleeding and only lasts for 1-2 days.