It makes sense since one third of them were wiped out by abortion.
Additional reasons:
* When someone thinks they are pregnant, diagnosis is often via sonogram. The first serious revelation is via “here’s the baby’s heartbeat”.
* People announcing an impending arrival via sonogram pictures and sending baby pictures of 4D sonograms. That makes it much more real.
* The availability of Depo Provera, IUDs and other long term use it and forget about it birth control methods, and their rapid uptake by teens, makes people much less sympathetic of “I forgot my pill, I forgot a condom” excuse for unplanned pregnancies. The reaction is more “You should have got the shot if you’re too irresponsible to handle a pill”.