In December, my son was born in Switzerland - still in process of getting a birth certificate for him. I am a US citizen living abroad. Is my son considered US Citizen?

I have lived and worked abroad for the entire year of 2016.  Is my son considered an 'accidental' American by default (i.e. US Citizen)?  As his birth certificate is still being processed, and being a prerequisite to officially apply for US citizenship, I am not certain what his official nationality would be.  Thank you.