On the prescription information for birth control pills:
A third way [this hormone medication prevents pregnancy] is by changing the womb lining, making it difficult for a fertilized egg to attach to the lining of the womb (implantation). A fertilized egg (embryo/unborn baby) needs to attach to the womb to receive blood and nutrients and continue to grow. If an embryo/unborn baby does not attach, it cannot survive.
So, obviously, this last indication — in addition to 1) preventing ovulation and 2) preventing the egg and sperm from getting friendly — is why anti-choice activists are coming out against birth control. To them, it’s the same as abortion (even though it actually isn’t).
That aside, the term “embryo/unborn baby” seems weird. Embryos aren’t viable, so calling them “unborn babies” doesn’t really make sense, since the word “baby” means a newly born human being–and by necessity, one that’s viable outside of the womb. There’s a squishiness about the phrasing that makes me wonder how it got onto the prescription info.