It is weird that this needs an explicit psak...

Chief Rabbi of Jerusalem Rav Shlomo Amar issued a psak that it is prohibited to abandon a child. While Rav Amar differentiates between abandoning a child in the streets and abandoning a child in the hospital is that while they are both prohibited, abandoning a child in the streets is like murdering him/her, while abandoning a child in the hospital is like disposing of the child and placing its sustenance on the public, which is prohibited.

Rav Amar said this in response to questions posed to him, among other rabbis, by The Puah Institute. According to published statistics, 200-300 newborn babies are abandoned in hospitals every year in Israel. In the majority of cases, these babies are abandoned due to having been born with birth defcts of sorts. In some cases it is for social or financial reasons.
source: Kipa

I suspect that people who would abandon a newborn baby would not have their minds changed by a psak on the matter.