Why do birth control pills increase the clotting risk?

I have read that birth control pills will increase the clotting risks. But I don’t understand the mechanism. Now I think I understand.

During birth, the risk of bleeding is high. During pregnancy, the production of blood clotting factors increases as a preventative measure.  Birth control pills are a mimic of pregnancy conditions. They will induce increased production of blood clotting factors. This will increase the risk of blood clotting.

This mechanism is quite simple. Yet the medical profession is reluctant even to acknowledge the relationship between birth control pills and blood clotting for many years.

The increased risk of blood clotting is another sacrifice mothers make.