Is it ethical to create a sentient AI that might suffer? -> we already make similar decisions millions of times per day
Don't treat humans as means to an end, instead treat them as ends -> we create other humans to satisfy our current needs in a world characterized by struggle
And of course as you have pointed out, some groups consider that it's better by default for a child to exist in adverse starting conditions (whilst also negatively impacting other people) than to not exist
We know the great mass of humans will carry on as before and there's little we can do to change that, but we are also aware that we have this responsibility that we can act on in our own life. Every person in the position to reproduce has a choice laid out before them. For the majority of us, it's the single most impactful ethical decision we will ever make.