What is the most common cause of bleeding during early pregnancy?

Implantation bleeding is recognized as the most common cause of bleeding during early pregnancy. This phenomenon occurs when the fertilized egg attaches itself to the uterine lining, a process that usually takes place about 6 to 12 days after conception. As the embryo implants into the endometrial tissue, it can cause light spotting or bleeding, which is often mistaken for a light menstrual period. This bleeding is typically minimal and brief and can serve as one of the early signs of pregnancy.

In early pregnancy, it's important to differentiate between various causes of bleeding. While other conditions such as placenta previa, ectopic pregnancy, and hormonal changes can also lead to bleeding, they are less common during this early timeframe. For instance, although ectopic pregnancy can cause significant bleeding, it occurs less frequently than implantation bleeding. Similarly, placenta previa is characterized by abnormal placental positioning and generally manifests later in pregnancy rather than in the early stages. Hormonal changes can lead to some spotting, but this is not often considered a cause of bleeding in clinical definitions. Thus, implantation bleeding stands out as the most common and a normal occurrence in the context of early pregnancy.