Birth certificate

A young friend of mine had this problem recently. Your wife should go to her village office and enquire about the registration of birth.  She should take the notice of birth from the hospital. This gives the babies sex, date and place of birth, and the mother's name. The village office will let her know what other documents they require. These are likely to include marriage certificate and family registration book.

If you have a marriage certificate, then your name can appear on the birth certificate, the child may have a foreign name, and you may choose either Vietnamese or foreign citizenship for your child.  Foreign citerzenship will be shown on the birth certificate.  If you do not have a marriage certificate, your child must take Vietnamese citizenship, have a Vietnamese name, and only the mother's name will be on the birth certificate. 

Good luck