I will argue that you have misstated the proposition.
The left kills babies as collateral damage to the actual desired result.
There are perhaps more than one primary abortion result. One is the overwhelming desire of women not to burden their lives with a child. Another is pure unadultrated fear of death during the birth process.
Eliminating the pregnacy burden has several forms including priority of a career, inability to absorb the economic hit and last just plain laziness.
No actual thought need be given to the actual killing.
Agreed, that is the big lie they have been told for 50 years.