Cultures that don’t practice infanticide are the exception in the historical and anthropological record. Not killing your children was invented by the Egyptians, taken up by the Jews and spread by the Christians, Muslims, presumably other Abrahamic faiths and cultures derived from them. It has not been obvious to the huge majority of people ever born that there was anything wrong with infanticide. If you think it is obviously wrong you might want to make an argument of some kind.

https://en.wikipedia.org/wiki/Infanticide

Well, I am a former embryo and fetus. I was given the opportunity to be born, and so I became pro-life. That seems like a pretty obvious and logical decision.