Implantation bleeding is a common and normal occurrence for many women during early pregnancy. It occurs when the fertilized egg implants itself into the lining of the uterus, causing some light spotting or bleeding. While it can be concerning for some women, implantation bleeding is usually not a cause for alarm and does not pose a risk to the pregnancy. Causes of Implantation Bleeding? Implantation bleeding occurs when the fertilized egg attaches itself to the lining of the uterus. This can cause light spotting or a light flow of blood, which is often mistaken for a period. It typically occurs about 10 to 14 days after conception, or around the time of a woman's expected menstrual period. How much blood is considered implantation bleeding ? Implantation bleeding is usually light and only involves a small amount of spotting or a light flow of blood. The amount of blood associated with implantation bleeding is generally much less than a regular menstrual period. Some women may on