New born registration: I am a foreigner living in china and my wife is Chinese.

Oh, China does not recognize dual nationality. If you register son in your embassy, it means that he is not Chinese. And he can only get your country's passport. Besides, person born in China one of whose parents is a Chinese national. Thus you can registter him under his mother's Hukou. The official staff will give your several documents and certificates to prove you are his father. Don't worry.