I’m assuming you are referring to this post.
The google definition of “Holocaust” is “destruction or slaughter on a mass scale, especially caused by fire or nuclear war.”
As a woman who is pro-life, I see abortion as a slaughter on a mass scale. Just over the past few decades 55 million children have been denied the right to be born. In my opinion, that is quite a lot more than the Holocaust that took place in Europe with 6 million Jews being murdered (not counting homosexuals, gypsies and other groups).
It is not antisemitic, it is comparing the wrong doings of those who persecuted the Jews with the legality of the destruction of children.
If you are pro-choice I can completely understand that, however I am not. And I do not believe that post is antisemitic at all.