Under this situation, two ways:
1) Get your wife here, and the baby born on America soil will be citizen by birth. You'd better do it now -- she might not get visa when her pragnancy is visible.
2) Deliver the baby in China -- nothing to be shamed of that, we are all Chinese, no matter our citizenship. You can immigrate him/her later. In this situation, you prefer to submit N-400 to become a citizen yourself because that shorten the process. GC can immigrate the mother and baby but the process is longer.
Good luck!
