Calling a pro-choice person a "murderer" is a sadly common inflammatory insult hurled by pro-birthers. In true medical terms, terminating an embryo is terminating a multicellular diploid eukaryotic organism, not murdering a person. Nonetheless, people still invoke images of infanticide in order to demonize people advocating for reproductive health care access. Normalizing a debate around whether abortion is murder has only further stigmatized the very real existential threats women face without birth control and safe abortion access.
A recent screenshot posted on the Murdered by Words subreddit showed a heated exchange between a pro-choicer and the pro-birth person who called them an advocate for murder.