Is there a connection between emergency contraception and ectopic pregnancy?

Patient's question:

Today I read about the principle of emergency contraception: it prevents the implantation of the fertilized egg. Suddenly, I thought: isn't that ectopic pregnancy? It's so scary. Can you answer that? What kind of help do you expect: I hope to get an explanation

Doctor's answer:

The active ingredient in emergency contraception is progesterone. Its primary mechanism of action is to inhibit the implantation of a fertilized egg. Only implantation outside the uterine cavity constitutes an ectopic pregnancy. An egg that cannot implant, of course, cannot lead to delivery. Therefore, there is no possibility of ectopic pregnancy. Your understanding is somewhat off. If the fertilized egg cannot implant, it transforms into something else. That's why emergency contraception is effective for breastfeeding, not for causing ectopic pregnancy.