I've seen posts on different sites (Reddit among others) where the mother found out the father was cheating or some similar circumstances and aborted very late in the pregnancy. Real or not, I have no idea, but it seems plausible for at least a few cases. Husband left, no job, no security, or they lost their job, mental health took a turn for the worse, lots of reasons why are given. I am pretty sure it does probably happen, but who knows how often?
For those not familiar, Reddit leans very far left.