Killing a baby is murder, and by the parents.
It’s Biblically horrendous.
There is another issue. and It is related. In fact, the theologians prove that it is causative.
Read Humanae vitae
http://www.vatican.va/holy_father/paul_vi/encyclicals/documents/hf_p-vi_enc_25071968_humanae-vitae_en.html
Just read it.
Now. To your point. The point people in this failing culture make, especially from the liberal point of view:
‘It’s incredibly unrealistic to expect that people will avoid intercourse if they don’t want children.’
Please, and very very simply, prove your point, and also tell us how We, in this time, from 50 years ago, are so correct, in our sudden dependence on the pharmaceutical industry for the first time in human history, that we are the only ones since the year 3500 BC who separate sex form birth, and marriage from sex?
Your observation that "we are the only ones since the year 3500 BC who separate sex form birth, and marriage from sex" strikes me as, well, not entirely accurate. Perhaps the more precise term for it would be disingenuous.
Do you really imagine that those of the current generation "are the only ones since the year 3500 BC" to have sexual relations outside of marriage? Or to have sexual relations for reasons other than a desire to reproduce?