You're splitting hairs.
Ethinyl estradiol and levonorgestrel are used together in this product as an emergency contraceptive (EC) to prevent pregnancy after contraceptive failure or unprotected intercourse. Ethinyl estradiol and levonorgestrel prevent ovulation (the release of an egg from an ovary), disrupt fertilization (joining of the egg and sperm), and inhibit implantation (attachment of a fertilized egg to the uterus).
At the very bottom of the page, after repeatedly stating that it won't terminate a pregnancy and isn't harmful if you're pregnant, it says: You should not take Plan B® One-Step if you are already pregnant.
Hmmmmm.
Right, that’s the third function, so it is designed to end a human life if the first two mechanisms fail.