you have to apply for AP

You are still H-1 as long as you remain in the U.S. But if you went back, you can't apply for H-1 any more. You have to apply for Advanced Parole to come back before you leave for China. Since your I140 has been approved yet, there is some risk using AP to come back to U.S. In your situation, I would suggest you ask your parent or somebody else to take your baby back.