Giving kids a happy childhood and setting them up for happiness and contentment is of course implied. Either way, I think the vast majority of people who are alive want to remain alive, so I never understood the sentiment that it's selfish to bring someone into the world. It's only selfish if you benefit while someone else suffers. Bringing kids into the world is a win-win, at least in the developed world where birthrates are plummeting way below replacement rate. In this case it's a win-win-win (third being society).

What might be considered selfish is to not have kids when we are way below replacement rate, while expecting to be taken care of by other's kids in old age. Unless we reach AGI and humanoid robots soon, the food, housing, services and healthcare has to be provided by younger people.