If part of your ethics are to do no harm, to prevent and mitigate suffering and to be unselfish shouldn't be the act of abortion be construed as a mercy? When a child is born into this world, I am 100% sure that it will suffer, most likely for the rest of its life, this is an act of causing harm. And what is child-bearing? What is the reason for it other than some selfish need? Other than someone gets it into their head that they want children regardless of the consequences of the act. That seems to me the epitome of selfishness. We cannot determine the fate of the child born into this world other than they will suffer and cause harm, so what makes you think that bringing a child to term is anything other than selfishness unless you find some means to prevent that suffering and that harm? If you can't then why have children other than your own selfish desire?
If you haven't already, you should look into antinatalism which is the position that humans shouldn't have children. There are quite a few flavours of antinatalism but since your post is concerned with suffering, that's what I'll focus on. I wanted to expand on this post to give people a bit more of the reasoning behind this particular branch of antinatalism.
To start with, there's a principle called negative utilitarianism which posits that the best ethical approach is to reduce suffering rather than increase happiness. This seems to be the basis of your post.
Now there's an important distinction to make with negative utilitarians which is whether the goal should simply be the reduction of suffering or the
elimination of suffering. If you take the latter view then antinatalism is the likely end result. Non-existence means a complete absence of suffering and so by bringing a consciousness into being, you're acting in an unethical manner by creating something capable of suffering.
Second, there's the stance that the potential for suffering outweighs the potential for joy. That can be interpreted in terms of negativity bias (that negative experiences have a greater emotional impact than otherwise equivalent positive experiences) or in terms of risk assessment or a combination of the two. Since we don't know what the future of our child holds, we have to consider the possibility that their life will be awful and weigh that against the possibility that it won't be. It's a gamble that some antinatalists argue isn't worth it, especially since negativity bias suggests that the impact of suffering will outweigh the impact of joy.
Finally, following on from the gambling idea, there's the fact that we don't know what your child or humanity itself will become. Your little bundle of joy could turn out to be the next Jack the Ripper or Stalin. Not only are you gambling on your own child's well-being, you're gambling with the well-being of others. Furthermore, humanity itself could find itself in a far worse situation than it currently is. While you may argue that life isn't currently all that bad, there's absolutely no guarantee that it will stay that way. We may end up scrabbling through the ruins of a post nuclear world within the next few decades. We just don't know.
So, all of that is intended to give a little background on why somebody might well argue that abortion really is a mercy. If you were to round up all the antinatalists of the world and ask them their stance on abortion, I'd put money on the majority being in favour. However, it's by no means universal and there are still those who are dead against it. They argue that a foetus constitutes a human life and that while it's unethical to create a life, it's at least equally wrong to end one.
People are of course free to agree or disagree with this stance on having children. Personally, I disagree with the view that having children is inherently selfish. The simple fact is that some people will see a greater capacity for joy and could give a perfectly logical argument that it's selfish
not to create a new life (for example, by taking a utilitarian view in which maximizing happiness is the goal). Ultimately, it has to be a choice.
I choose not to have children.