Denying that a woman would ever "kill for convenience" her 3rd trimester unborn baby seems disingenous to me. Women/girls have been known to give birth to a baby they don't want to raise (because it would be "inconvenient") and put it in a dumpster to die. Its rare (thank gawd), but I've heard stories about this since I was a kid. I recall a few years ago a pregnant teen girl gave birth to her baby during her prom, put it in a trash can and returned to the dance floor afterwards.
IIRC, at least in California such behavior inspired a law allowing newborn babies to be dropped off anonomously at a local fire station or hospital, no questions asked. If some women/girls are capable of killing a newborn baby, don't you think they would have no problem aborting a baby/fetus in the third trimester, given the means and opportunity?