SPOILER - Killing the ___ the Right Thing to Do?

Given the circumstances that Isagel knew at the time, and which turned out to be true, that they would eventually not be able to farm any more food, was it the right thing to do, to kill her child? Mercy kill, so he wouldn't have to grow up and starve or kill himself in the future?

Having children if there was still hope of turning around or of rescue, fine, but if someone came to the conclusion that it was futile, then even getting pregnant would be highly irresponsible and maybe the moral thing to do was to not raise the child. The only other thing I can think of is the murder-suicide's effect on the Mimarobe and how it would have been more moral to convince her to go with them, instead of leaving her to discover them - in the most dreadful scene of the entire movie - and be left alone.