If a single mother struggles it's because she deserves it. If her child suffers for that struggle it's her fault. So long as there's something or someone to blame, you can ignore the question of how you could have prevented the problem in the first place.
In fact, if you provide her support, you might be rewarding her infidelity. And then people will perceive that as a reasonable thing to do and more people will do it and then and then and then....
But the important thing is that she didn't "sin" by "killing the baby". If the baby dies after it's born, it's also her fault.
Like I said, there's no hypocrisy there. Being a hypocrite isn't the worst thing someone can be. It's entirely possible to have a perfectly (or as perfectly as humans are capable of) self-consistent worldview that is also incredibly cruel. I think a lot of people have lost sight of that.
At some point people started to believe that conservativism was about "preserving the past" but that's subtly wrong. It's about "preserving hierarchies". Recognizing that all people are worthy of life is contrary to the idea that some people deserve what's coming to them.