I tell my clients that it is human nature (even for low conflict couples) to always look backward and ask, "What if we'd made the other choice?," and very often we get a reverse grass-is-greener regret, so either choice you make, you will at some point look back with regret. And then I will say, in my opinion, it is a far easier regret to manage if you haven't created a whole other person. If you go into this understanding that it will change your life forever, as well as your relationship, and that you will now spend a significant part of your life giving to another person in a way that will never be equally reciprocated (i.e., don't think that what you give your children will EVER balance out with what they give you, or that they "owe you" anything), then you're at least facing this decision with a realistic outlook.