A few months ago, political commentator Ben Shapiro tweeted that according to Judaism, abortion is murder. This led to criticism from one rabbi as overly simplistic and then defense by another, who showed that both Rav Moshe Feinstein and Rav Joseph B. Soloveitchik called abortion murder.
Below is a report from Rav Ya’akov Kamenetsky’s 1970 Shabbos Shuvah derashah, in which he calls abortion a form of murder after 40 days from inception — before 40 days it is forbidden for a different reason. While this was not said as a specific ruling, neither was Shapiro’s tweet. At the very least, Rav Kamenetsky’s lecture reflects a general attitude.
(Of course, all such cases should be discussed with a competent rabbi.)