Not the parent, but I have some experience here - my cofounder and I both had kids a month apart (four years ago). It switches you to playing the startup game in "hard mode", but it is doable with the right spouse(s).
YMMW, but FWIW. You no longer have the luxury of hours-long uninterrupted coding streaks, but it doesn't prevent you from thinking through things that need to be done (e.g. when you are walking outside with a stroller). The net effect of it is that when you do have a chance to sit down and code, you produce something that requires no rewriting or refactoring later on. If you then compare time it takes to get X done, the think-then-code comes on top of code-then-rewrite and by a large margin.
In a sense having a baby forces you to become a more thoughtful and effecient programmer :)