Because childbirth is most often VOLUNTARY. Abortion is legal, and a fast efficient cure for being pregnant, hardly a missed day, heart attack on the other hand, not so fast and easy a cure, you gotta eat right and excersize and have good genes and all sorts of stuff. Not so fast not so easy, and truthfully not so cheap.
BTW I do not like abortion, but I will not decide what another may do with her body. (and until birth that baby IS a part of Moms body)
As far as men not knowing how hard childbirth is, there is a reason God gave that gift/curse to us, we can take it, they can't.
Also men have a need to protect women from harm (we do to) so the idea that they CAUSED the problem and canNOT fix it is very hard for them to assimilate, so the lesser men, ignore it and pretend it doesn't exist. (the better ones, those you marry, which is why there are more better ones now than before)