If in expectation a life involves more suffering than happiness, then it is immoral to create such a life. I think that that is not the case, for most people, there is more happiness than suffering. We justify making the choice for an as-yet-non-existent person the same way we justify making all choices for very small children, and gradually fewer choices as the child gets older: until they are able to make a decision for themselves, somebody else has to make it for them, and all we can do is give the decision to someone we think will act in the child’s best interests.
If in expectation a life involves more suffering than happiness, then it is immoral to create such a life. I think that that is not the case, for most people, there is more happiness than suffering. We justify making the choice for an as-yet-non-existent person the same way we justify making all choices for very small children, and gradually fewer choices as the child gets older: until they are able to make a decision for themselves, somebody else has to make it for them, and all we can do is give the decision to someone we think will act in the child’s best interests.
As a rule of thumb: (1) are you happy that you exist? (2) do you have a reason to believe that your children will have life worse than you?